||Purchased this product in hopes of getting my custom M4 into the high 400's fps. Purchased this along with 70% bucking, Madbull tightbore barrel, G&G Super Torque motor, and an 11.1 LiPo. Basically everything you should need to produce 500fps. Well installed everything and to my dissapointment this mech box will only produce low 400's (423) was the best I chrono'ed. for the cost of what I purchased I would have liked to see better results.
1. Its much cheaper then Systema
2. Its LiPo ready
3. 8mm Bearings
4. Reinforced gears
1. Should state in description that also requires other products to produce the FPS claimed
(tightbore barrel, HARD bucking, High Torque Motor, and Large power battery)
2. Even with all pieces needed to work right still only hits low 400's which I can do on my stock Classic Army Gear Box with an M115 spring for less then 20 bucks.
Over all I would not purchase this item again if I could do over, maybe I got a lemon.
Rating: [2 of 5 Stars!]