With double-acting models, the pressure increase is made possible by means of the area ratio between the larger diameter air drive piston directly connected to two smaller diameter gas pistons. These latter having the same diameter as each other. The reciprocating action of the gas booster draws gas at low pressure into the booster then displaces the gas at a higher pressure output from the booster into a closed system. On double-acting models, the inlet gas pressure is used to provide additional energy allowing greater output pressures and higher flowrates to be achieved. All Models can easily be incorporated into easy to operate Standard System gas power/transfer units.