A portable gas cylinder (10, 210) comprising: a gas tank (12, 212) having an upper portion, a lower portion (18, 218), and a collar (20, 220), the collar (20, 220) including a base (22, 222) secured to the lower portion (18, 218), a flange (24, 224) extending around and radially outwardly from the base (22, 222); and a foot ring (14, 214) configured to be attached to the gas tank (12, 212), the foot ring (14, 214) including: a base (32, 232) having an inner surface (34, 234), an outer surface (36, 236), a central portion (38, 238) and an outer peripheral portion; a plurality of circumferentially spaced deflectable longitudinal lock tabs (90, 290) extending around the base (32, 232) for securing the foot ring (14, 214) to the tank (12, 212), each of the circumferentially spaced deflectable longitudinal lock tabs (90, 290) having a first projection (92, 292) with an inner surface configured to abut a radially outer surface of the flange (24, 224); characterized in that: the collar (20, 220) of the gas tank (12, 212) includes a plurality of notches (26, 226) circumferentially spaced around the flange (24, 224); each of the circumferentially spaced deflectable longitudinal lock tabs (90, 290) has a catch (94, 294) extending from the respective first projection (92, 292) for engaging an underside of the flange (24, 224) to secure the foot ring (14, 214) to the tank (12, 212); and the foot ring (14, 214) includes a plurality of circumferentially spaced deflectable rotational lock tabs (110, 310) extending around the base (32, 232) for preventing rotational movement of the foot ring (14, 214) relative to the tank (12, 212), each of the circumferentially spaced deflectable rotational lock tabs (110, 310) having a second projection (112, 312) configured to be received in a respective one of the notches (26, 226). a gas tank (12, 212) having an upper portion, a lower portion (18, 218), and a collar (20, 220), the collar (20, 220) including a base (22, 222) secured to the lower portion (18, 218), a flange (24, 224) extending around and radially outwardly from the base (22, 222); and a foot ring (14, 214) configured to be attached to the gas tank (12, 212), the foot ring (14, 214) including: a base (32, 232) having an inner surface (34, 234), an outer surface (36, 236), a central portion (38, 238) and an outer peripheral portion; a plurality of circumferentially spaced deflectable longitudinal lock tabs (90, 290) extending around the base (32, 232) for securing the foot ring (14, 214) to the tank (12, 212), each of the circumferentially spaced deflectable longitudinal lock tabs (90, 290) having a first projection (92, 292) with an inner surface configured to abut a radially outer surface of the flange (24, 224); a base (32, 232) having an inner surface (34, 234), an outer surface (36, 236), a central portion (38, 238) and an outer peripheral portion; a plurality of circumferentially spaced deflectable longitudinal lock tabs (90, 290) extending around the base (32, 232) for securing the foot ring (14, 214) to the tank (12, 212), each of the circumferentially spaced deflectable longitudinal lock tabs (90, 290) having a first projection (92, 292) with an inner surface configured to abut a radially outer surface of the flange (24, 224); the collar (20, 220) of the gas tank (12, 212) includes a plurality of notches (26, 226) circumferentially spaced around the flange (24, 224); each of the circumferentially spaced deflectable longitudinal lock tabs (90, 290) has a catch (94, 294) extending from the respective first projection (92, 292) for engaging an underside of the flange (24, 224) to secure the foot ring (14, 214) to the tank (12, 212); and the foot ring (14, 214) includes a plurality of circumferentially spaced deflectable rotational lock tabs (110, 310) extending around the base (32, 232) for preventing rotational movement of the foot ring (14, 214) relative to the tank (12, 212), each of the circumferentially spaced deflectable rotational lock tabs (110, 310) having a second projection (112, 312) configured to be received in a respective one of the notches (26, 226).