comes with everything shown, it doesn't say in the description, but when i got the gears they were rated to an M155. I'm using mine with an m140 and a high torque motor, they didn't pull the m140 back with an 8.4 V battery so use a 9.6 or higher. they are a bit nosier, and does slow ROF quite significantly, i might get 4-5 rounds a second but i think its worth it to pull a powerful spring.
the gears them self looked high quality, but the gear that connects with the piston had a defect on the shaft going through it, which i needed to ground down, it did make shimming difficult- just warning any buyers they may have to do the same.
-plenty of extra shims
-had to grind that defect off which made shimming difficult
-i agree with the other post that the piston doesn't look the best but once again that's not why i bought the package.
Rating: [5 of 5 Stars!]