The standard is a cylinder
On this page11
The requirement is one sentence and it does not contain a measurement
No toy or other children’s article subject to the regulation shall be small enough to fit entirely within a cylinder with the dimensions shown in Figure 1.
Which is unlike every other spine described across this library
A concentration in parts per million. A burn time in seconds. A diameter in microns. A percentage by weight. A surface area fraction. A capacity in milliliters. All of them are numbers in the text.
This one is a drawing of a piece of equipment
The dimensions live in a figure and the test is whether the object drops into the thing. Which makes the standard a fixture rather than a value.
That has a practical consequence worth naming
A gauge test gives a single answer to a question that would otherwise need several measurements. An irregular object has no one diameter, and asking whether it fits a cylinder settles every axis at once.
No page here reproduces the cylinder’s dimensions
Because the governing figure is a drawing, including a sloped base, and a number quoted out of it would be a worse record than a pointer to the rule. The reference at the foot of this page names the section.
And no page here performs or reports a test
Nothing on this property says whether any article would or would not fit the cylinder. That is a test somebody performs on a physical object with the Commission’s apparatus.
The enforcement fixture carries a one-sided tolerance
The dimensions of the Commission’s test cylinder will be no greater than those shown in the figure. So the gauge used in enforcement is at or under the stated size, which makes a marginal article marginally more likely to pass.
A stated tolerance running in one direction only is rare in this library
Most thresholds are a flat ceiling or floor. This one says the apparatus will not be larger than specified, which is a statement about the measuring instrument rather than about the thing measured.
And the hazard it is standing in for is named precisely
A choking, aspiration, or ingestion hazard because of small parts. Three distinct mechanisms, and the cylinder is a single proxy for all three.
None of which reaches anything in this group
A contact lens case, a cufflink box, an earplug carrier, a hair tie, a travel jewelry roll and a travel sewing kit are not toys or articles intended for use by children under three, and nothing on these pages says they are.