46 CFR § 78.47-30
Hand portable fire extinguishers
April 15, 2021
(a) Each hand portable fire extinguisher shall be marked with a number and the location where stowed shall be marked with a corresponding number at least 1⁄2 inch high. Where only one type and size of hand portable fire extinguisher is carried, the numbering may be omitted.
(b) [Reserved]