A portable gas cylinder comprising: a gas tank having an upper portion, a lower portion , and a collar , the collar including a base secured to the lower portion , a flange extending around and radially outwardly from the base ; and a foot ring configured to be attached to the gas tank , the foot ring including: a base having an inner surface , an outer surface , a central portion and an outer peripheral portion; a plurality of circumferentially spaced deflectable longitudinal lock tabs extending around the base for securing the foot ring to the tank , each of the circumferentially spaced deflectable longitudinal lock tabs having a first projection with an inner surface configured to abut a radially outer surface of the flange ; characterized in that : the collar of the gas tank includes a plurality of notches circumferentially spaced around the flange ; each of the circumferentially spaced deflectable longitudinal lock tabs has a catch extending from the respective first projection for engaging an underside of the flange to secure the foot ring to the tank ; and the foot ring includes a plurality of circumferentially spaced deflectable rotational lock tabs extending around the base for preventing rotational movement of the foot ring relative to the tank , each of the circumferentially spaced deflectable rotational lock tabs having a second projection configured to be received in a respective one of the notches . a gas tank having an upper portion, a lower portion , and a collar , the collar including a base secured to the lower portion , a flange extending around and radially outwardly from the base ; and a foot ring configured to be attached to the gas tank , the foot ring including: a base having an inner surface , an outer surface , a central portion and an outer peripheral portion; a plurality of circumferentially spaced deflectable longitudinal lock tabs extending around the base for securing the foot ring to the tank , each of the circumferentially spaced deflectable longitudinal lock tabs having a first projection with an inner surface configured to abut a radially outer surface of the flange ; a base having an inner surface , an outer surface , a central portion and an outer peripheral portion; a plurality of circumferentially spaced deflectable longitudinal lock tabs extending around the base for securing the foot ring to the tank , each of the circumferentially spaced deflectable longitudinal lock tabs having a first projection with an inner surface configured to abut a radially outer surface of the flange ; the collar of the gas tank includes a plurality of notches circumferentially spaced around the flange ; each of the circumferentially spaced deflectable longitudinal lock tabs has a catch extending from the respective first projection for engaging an underside of the flange to secure the foot ring to the tank ; and the foot ring includes a plurality of circumferentially spaced deflectable rotational lock tabs extending around the base for preventing rotational movement of the foot ring relative to the tank , each of the circumferentially spaced deflectable rotational lock tabs having a second projection configured to be received in a respective one of the notches . <EOS>