This AUSGEL upgrade spring has 1.18mm wire diameter and is compatible with the majority of battery powered blasters. Both ends have been flat ground to reduce wear on spring retainers and the inside face of your piston.
This is the latest version of the M401 WELL gearbox, includes bearings on the bevel gear and an extra reinforcing screw behind the spur gear. These gearboxes are now wired with long rear battery wires so you no longer need...