46 CFR 160.064-2 - Types and models.
(a) Types. Water safety buoyant devices covered by this subpart shall be of two general types, viz, those intended to be worn on the body and those intended to be thrown.
(b) Models. Water safety buoyant devices may be of different models which incorporate characteristics considered valuable for safety in various fields of water sports or boating activities.
(c) Sizes. Water safety buoyant devices designed to be worn shall be of sizes suitable for adults or children, as intended and marked on the device. Water safety buoyant devices intended to be thrown in water shall be of a minimum size intended for adults.
(d) Dimensions. A foam cushion designed to be thrown must be 2 inches or more in thickness and must have 225 or more square inches of top surface area.