33 C.F.R. § 175.21 Condition; size and fit; approval marking.
Title 33 - Navigation and Navigable Waters
No person may use a recreational boat unless each PFD required by §175.15 of this part or allowed by §175.17 of this part is: (a) In serviceable condition as provided in §175.23; (b) Of an appropriate size and fit for the intended wearer, as marked on the approval label; and (c) Legibly marked with its approval number, as specified in 46 CFR part 160. [CGD 81–023, 55 FR 32034, Aug. 6, 1990, as amended by CGD93–055, 61 FR 13926, Mar. 28, 1996]
Title 33: Navigation and Navigable Waters
PART 175—EQUIPMENT REQUIREMENTS
Subpart B—Personal Flotation Devices
§ 175.21 Condition; size and fit; approval marking.

