This publication is for the self-contained underwater breathing apparatus (SCUBA) cylinder owners, users, and facilities that sell, charge, perform annual inspections, and retest SCUBA cylinders. It contains information on the crown marking, charging, maintenance, handling, storage, inspection, retesting, cleaning, and refinishing of SCUBA cylinders. P-5 will answer most common questions of the SCUBA cylinder owner and user or lead them in the direction to find the answers.