SHS M100 AEG Spring.
For all V2/3/4/6/7gearboxes, and for all ranges of AEG by Marui (non NGRS range), G&G, LCT, G&P, VFC, Cyma, JG to name a few....
FPS around 340-350fps on most AEG's but all guns vary due to air seal, we strongly recommend getting your gun put through a chronograph after fitting.