46 CFR 160.002-6 - Marking.
Each life preserver must have the following clearly marked in waterproof ink on a front section:
(a) In letters three-quarters of an inch or more in height:
(1) Adult (for persons weighing over 90 pounds); or
(2) Child (for persons weighing less than 90 pounds).
(b) In letters that can be read at a distance of 2 feet: