Brady pipe markers for the medical industry are designed to wrap completely around 3/4" piping. 3" x 3" markers come complete with direction flow arrows with 1/4" high characters. These pipe markers comply with CGA & NFPA Standards:· National Fire Protection Assoc. (NFPA) Standard 99C-1996 NFPA 99C- Section 4-18.104.22.168: The gas content and operating pressure of medical gas piping systems shall be identifiable by labeling with name and pressure of the gas contained. Labeling shall appear at intervals not more than 20 ft. and at least once in each room and each story traversed by the piping system.· Compressed Gas Assoc. (CGA) Pamphlet C-9-1988 (R1993)CGA C-9-Section 4.1: Colors identification of piping is used in accordance with gases and colors named in CGA Pamphlet. Color coding is never to be used alone; it is supplementary to labeling.