An SCBA backpack for holding air cylinders, comprising: a) a chassis with a cradle receiving arrangement, wherein the cradle receiving arrangement has a longitudinal axis, a base, a pair of upper walls (153A, 153B) protruding from the base, and a pair of lower walls (150A, 150B) protruding from the base and offset from the pair of upper walls (153A, 153B), each of the upper walls (153A, 153B) and the lower walls (150A, 150B) having a bore (152A, 152B, 154A, 154B) extending therethrough, wherein the base, the pair of upper walls (153A, 153B), and the pair of lower walls (150A, 150B) define at least one cavity such that the at least one cavity extends between the pair of upper walls (153A, 153B) and the pair of lower walls (150A, 150B); and b) a tank cradle for holding at least one air cylinder, wherein the tank cradle has an attaching arrangement configured to directly or indirectly interact with the cradle receiving arrangement of the chassis to thereby removably secure the tank cradle to the chassis via a single attaching member that extends through the bores (154A, 154B) of the pair of upper walls (153A, 153B), the bores (152A, 152B) of the pair of lower walls (150A, 150B) and across the at least one cavity of the cradle receiving arrangement and through at least one bore (147A, 147B) of the attaching arrangement located on a projection (145A, 145B, 148A, 148B) extending from a body of the tank cradle, wherein (i) the attaching arrangement includes a first set of projections (145A, 145B) at one end of a cradle base, each having a bore (147A, 147B) extending therethrough, and a second set of projections (148A, 148B) at a second end of the cradle base, wherein each projection has a bore (149A, 149B) extending therethrough; (ii) the attaching arrangement of the tank cradle is received within the at least one cavity defined by the cradle receiving arrangement; and (iii) the projections (145A, 145B, 148A, 148B) are shaped to engage the walls (150A, 150B, 153A, 153 B) to locate and non-rotatably secure the cradle base to the chassis body and when the cradle base is mounted on, to, or within the cradle receiving arrangement, the bores (147A, 147B, 149A, 149B) of the respective projections (145A, 145B, 148A, 148B), and of the respective walls (150A, 150B, 153A, 153B) are substantially aligned with one another, such that the attaching member may be inserted within the bores (147A, 147B, 149A, 149B, 152A, 152B, 154A, 154B) to secure the cradle base to the chassis body. a) a chassis with a cradle receiving arrangement, wherein the cradle receiving arrangement has a longitudinal axis, a base, a pair of upper walls (153A, 153B) protruding from the base, and a pair of lower walls (150A, 150B) protruding from the base and offset from the pair of upper walls (153A, 153B), each of the upper walls (153A, 153B) and the lower walls (150A, 150B) having a bore (152A, 152B, 154A, 154B) extending therethrough, wherein the base, the pair of upper walls (153A, 153B), and the pair of lower walls (150A, 150B) define at least one cavity such that the at least one cavity extends between the pair of upper walls (153A, 153B) and the pair of lower walls (150A, 150B); and b) a tank cradle for holding at least one air cylinder, wherein the tank cradle has an attaching arrangement configured to directly or indirectly interact with the cradle receiving arrangement of the chassis to thereby removably secure the tank cradle to the chassis via a single attaching member that extends through the bores (154A, 154B) of the pair of upper walls (153A, 153B), the bores (152A, 152B) of the pair of lower walls (150A, 150B) and across the at least one cavity of the cradle receiving arrangement and through at least one bore (147A, 147B) of the attaching arrangement located on a projection (145A, 145B, 148A, 148B) extending from a body of the tank cradle, (i) the attaching arrangement includes a first set of projections (145A, 145B) at one end of a cradle base, each having a bore (147A, 147B) extending therethrough, and a second set of projections (148A, 148B) at a second end of the cradle base, wherein each projection has a bore (149A, 149B) extending therethrough; (ii) the attaching arrangement of the tank cradle is received within the at least one cavity defined by the cradle receiving arrangement; and (iii) the projections (145A, 145B, 148A, 148B) are shaped to engage the walls (150A, 150B, 153A, 153 B) to locate and non-rotatably secure the cradle base to the chassis body and when the cradle base is mounted on, to, or within the cradle receiving arrangement, the bores (147A, 147B, 149A, 149B) of the respective projections (145A, 145B, 148A, 148B), and of the respective walls (150A, 150B, 153A, 153B) are substantially aligned with one another, such that the attaching member may be inserted within the bores (147A, 147B, 149A, 149B, 152A, 152B, 154A, 154B) to secure the cradle base to the chassis body.