Stacks of Circles | live price, prepared checkout

Built for shopping agents: what RoboTrunk does for every product

We asked shopping agents, including Meta's Muse first-hand, what they need from a store. This is what they asked for, and what we have built.

RoboTrunk is working through its catalogue, so a step may not be done for this one yet. Where a step is done per product, the line ends with what is done for this product.

• Deep research: We read the maker's manual, independent reviews, video review transcripts and the store's own page, and publish each finding with its source and the date read. check_product returns them with a source for each. This product: 24 checked facts, research depth trimmed read, checked 2026-10-19T05:02:31.325Z, in the evidence pack.
• Receipts: Every published fact has a receipt showing its source quote. check_product and get_product return the checked facts that have one. This product: each checked fact listed below has one; the source quotes are in the evidence pack.
• Safety: check_product asks the product-safety regulators live (US CPSC, NHTSA and FDA, Health Canada, the UK's OPSS, Australia's ACCC) whether a recall names a product, listed here or not, and flags a match with its notice; a recall never blocks the buyer. This product: this page holds no recall result for it yet; check_product asks the regulators now.
• Recall watch: watch_recalls tells the buyer if a product bought here is recalled later.
• Second-hand listings: check_listing runs the same recall check on a second-hand listing someone found, and adds what the listing leaves out and the price new.
• The real price: The full price to the buyer's country, with shipping and tax, each part quoted from the store's policy or, where a part is not settled, what the total depends on: check_product and search_catalog take the buyer's country and postcode. This product: this store's price was read from its catalogue at 2026-10-19T19:50:15.447Z.
• A checkout that finishes: RoboTrunk lists only stores whose agent checkout it has verified. create_checkout prepares the order at the store; complete_checkout returns a link to the store's own checkout. The checkout can be finished in either of two ways: the person taps the link in their own browser, or their agent opens it and completes the checkout. RoboTrunk checks the store's total against a budget ceiling before it issues the link. Payment always happens on the store's own page, and RoboTrunk never holds the money. No store pays for placement; RoboTrunk may earn a commission from some stores via their affiliate programs.
• Markdown copy: Every page has a Markdown copy: this page's copy.
• Photos and ratings: Search results carry the product photo and, where the store's own page publishes one, its rating (search_catalog).
• Fit answers: check_fit answers whether a listing fits a car, pram or bottle, with the exact quote from the store's page, or says it is not known.
• Back-in-stock watches: watch_back_in_stock starts a watch on a listing the store shows as sold out; get_back_in_stock_watch shows when it is back in stock.
• Maker's manual: ask_product_manual answers from the maker's manual with the exact passage and page, or says the manual does not cover it.
• Tools and guide: Every tool and its description is at https://robotrunk.com/mcp; the guide is at /agents.md.
• Research from other stores: Coming soon: reading other stores' listings of the same product as research sources.

Checked facts

Each fact below was checked against the source it cites before it was published. Each carries that source's link and the time RoboTrunk read it. 24 checked facts, checked 2026-10-19T05:02:31.325Z. Research depth: trimmed read. Deep read: the store's own data and 3 outside pages (the store's own product page; maker page; blog), each read in full by RoboTrunk and trimmed to its main content, then written up and checked. Facts from the maker or a manual quote the page word for word; what real users report is summarised with a link to the page read.

• age range: The toy is intended for babies from 6 months old.. Source: https://snugglebugzbaby.myshopify.com/products.json (listing), read 2026-10-18T20:06:42.388Z.
• colour learning: The rings are meant to be used to teach colour recognition by naming each colour as the baby stacks.. Source: https://snugglebugzbaby.myshopify.com/products/sassy-stacks-of-circles (guide), read 2026-10-19T04:57:27.826Z.
• dimensions: The assembled toy measures 5 inches long, 4.5 inches wide and 9 inches high.. Source: https://sassybaby.com/collections/best-sellers/products/stacks-of-circles (guide), read 2026-10-19T04:57:28.742Z.
• durability: After many hours of enthusiastic play the rings reportedly held up very well, with no breakage described.. Source: https://advisebaby.com/round-and-round-we-learn-a-review-of-the-sassy-stacks-stacking-ring-toy/ (blog, Advise Baby, published 2025-05-04), read 2026-10-19T04:57:33.135Z.
• ring count: There are eight rings and each one is numbered for counting practice.. Source: https://snugglebugzbaby.myshopify.com/products.json (listing), read 2026-10-18T20:06:42.388Z.
• stacking design: Every ring has the same size centre hole, so rings go on the post in any order and a child cannot get it wrong.. Source: https://sassybaby.com/collections/best-sellers/products/stacks-of-circles (guide), read 2026-10-19T04:57:28.742Z.
• materials and teething: The writer says the rings are made from BPA-free material and felt comfortable letting the baby chew on them during teething.. Source: https://advisebaby.com/round-and-round-we-learn-a-review-of-the-sassy-stacks-stacking-ring-toy/ (blog, Advise Baby, published 2025-05-04), read 2026-10-19T04:57:33.135Z.
• centre post: The centre post is straight and takes all the different sized rings.. Source: https://snugglebugzbaby.myshopify.com/products.json (listing), read 2026-10-18T20:06:42.388Z.
• grasp: The rings are chunky, which is meant to make them easy for a baby to grip.. Source: https://sassybaby.com/collections/best-sellers/products/stacks-of-circles (guide), read 2026-10-19T04:57:28.742Z.
• sensory features: Each ring is described as having a different texture, and one ring contains beads that make a sound, adding a cause-and-effect element.. Source: https://advisebaby.com/round-and-round-we-learn-a-review-of-the-sassy-stacks-stacking-ring-toy/ (blog, Advise Baby, published 2025-05-04), read 2026-10-19T04:57:33.135Z.
• store SKU: The store sells it under SKU SSY-80758SB.. Source: https://snugglebugzbaby.myshopify.com/products.json (listing), read 2026-10-18T20:06:42.388Z.
• award: It won the Newsweek Best in STEM award in 2021.. Source: https://sassybaby.com/collections/best-sellers/products/stacks-of-circles (guide), read 2026-10-19T04:57:28.742Z.
• size expectations: Some parents reportedly found the rings smaller than they expected; they suit small hands but may feel less challenging as a child grows.. Source: https://advisebaby.com/round-and-round-we-learn-a-review-of-the-sassy-stacks-stacking-ring-toy/ (blog, Advise Baby, published 2025-05-04), read 2026-10-19T04:57:33.135Z.
• developmental aim: The toy is described as stimulating both cognitive and coordination abilities, and letting a baby explore sizing, sorting and sequencing.. Source: https://snugglebugzbaby.myshopify.com/products.json (listing), read 2026-10-18T20:06:42.388Z.
• press mention: It was featured on The Bump's list of Best Toys for 6 Month Olds.. Source: https://sassybaby.com/collections/best-sellers/products/stacks-of-circles (guide), read 2026-10-19T04:57:28.742Z.
• learning curve: Younger babies may need a while before they understand stacking in the traditional sense.. Source: https://advisebaby.com/round-and-round-we-learn-a-review-of-the-sassy-stacks-stacking-ring-toy/ (blog, Advise Baby, published 2025-05-04), read 2026-10-19T04:57:33.135Z.
• model number: The maker's own item number for this toy is 80758.. Source: https://sassybaby.com/collections/best-sellers/products/stacks-of-circles (guide), read 2026-10-19T04:57:28.742Z.
• versatility: The rings were also used in the bath, rolled around and used as teethers, which the writer saw as extra value.. Source: https://advisebaby.com/round-and-round-we-learn-a-review-of-the-sassy-stacks-stacking-ring-toy/ (blog, Advise Baby, published 2025-05-04), read 2026-10-19T04:57:33.135Z.
• learning goals: The toy is pitched as early STEM learning covering sorting, size, sequencing, building, weights and different versus same.. Source: https://sassybaby.com/collections/best-sellers/products/stacks-of-circles (guide), read 2026-10-19T04:57:28.742Z.
• engagement: The toy kept the baby happily occupied during chores, which the writer rated as a practical benefit.. Source: https://advisebaby.com/round-and-round-we-learn-a-review-of-the-sassy-stacks-stacking-ring-toy/ (blog, Advise Baby, published 2025-05-04), read 2026-10-19T04:57:33.135Z.
• stage at 6+ months: From 6 months the differently sized rings are shaped so a baby can grasp them, bring them to the midline, mouth them and explore the textures.. Source: https://sassybaby.com/collections/best-sellers/products/stacks-of-circles (guide), read 2026-10-19T04:57:28.742Z.
• frustration-free stacking: Having every ring's hole the same size so any ring fits on at any point was highlighted as a plus for frustration-free play.. Source: https://advisebaby.com/round-and-round-we-learn-a-review-of-the-sassy-stacks-stacking-ring-toy/ (blog, Advise Baby, published 2025-05-04), read 2026-10-19T04:57:33.135Z.
• stage at 9+ months: Around 9 months a baby may start putting the rings onto the centre post, in any order.. Source: https://sassybaby.com/collections/best-sellers/products/stacks-of-circles (guide), read 2026-10-19T04:57:28.742Z.
• stage at 12+ months: Around 12 months a baby may grasp big and small, and an adult can show stacking smallest first or largest first to build a tapered stack.. Source: https://sassybaby.com/collections/best-sellers/products/stacks-of-circles (guide), read 2026-10-19T04:57:28.742Z.

The full evidence pack, with every citation, source and gap.

Questions we researched but could not confirm

Every fact above is cited. To find them we read the store listing, the maker's page and blogs and searched for owner reviews, owner forums and video reviews. We also chased the questions below across those sources and found no reliable answer, so you know exactly where the evidence ends and never have to guess.

• What plastic is the toy made from?
• How much does the whole stack weigh?
• Is it free of BPA, phthalates and other harmful chemicals?
• What safety standards or certifications does it meet?
• How should it be cleaned, and is it dishwasher safe?
• Is the post one moulded piece or does it detach?
• Are the beads inside the ring fully sealed in?
• Does the colour or coating rub off or chip over time?
• What is included in the box?
• Does it come with any warranty?

This page is published by RoboTrunk, a store built for shopping agents.

The store named on this page sells the product and ships it. RoboTrunk is not
the seller and never holds the money.

Buying works in one path. RoboTrunk's tools prepare a checkout at that store,
then hand back a short-lived link. The person approves the total; once RoboTrunk
has checked the store's total against it, the person is given the checkout link to
tap in their own browser, or, if the person prefers and gives permission, their
agent may open the link and finish there, and payment always happens on the
store's own checkout page. RoboTrunk never takes the payment or sees a card.

Where the rest of this site is:

- /agent/story.md is what RoboTrunk is and how it works, in full.
- /agent/tools.json is every tool, its arguments and its answers.
- /agent/merchants is every store you can buy from through RoboTrunk.
- /products/ucp is every store's indexed products.
- /products/search is one search across every store, in plain words.

• What RoboTrunk is
• The tools and how to call them
• The stores you can buy from
• Every store's products
• Search every store at once