If you're looking for big servo power then this could be the answer.
But be warned. They are big and heavy.
3.4 : 1 power boost ratio at 600mm Hg vacuum.
Canister diameter 270mm. Overall length 525mm.
Vacuum inlet male M14 x 1.5mm thread on each canister.
Fluid inlet and outlet female threads on cylinders 1/2" UNF.
(Note: If you prefer 3/8" UNF, purchase adapters, part number #BU1238 seperately).
Cylinder piston diameter 7/8"
Fluid bleed screw on each cylinder.
Four 3/8" UNF mounting studs on each end of canister flange. Weight 14 Kg.
LARGE HIGH POWER DUAL CIRCUIT REMOTE SERVO #RS270DUAL