RM4 Series AEG3 M120 Main Spring

The KWA RM4 Series AEG3 M120 spring is specially made to work with the KWA RM4 Kinetic Feedback System (KFS), and is made of hardened spring steel.  It fits in both the original RM4 PTS Scout and CQB models as well as the new rear-wired RM4A1, and is rated at around 390-410 FPS.

An essential feature on the new rear-wired RM4A1 as well the new RM4 AEG3 variants is the addition of spring quick-change abilities, so you can easily move from the field to a CQB setting (or vice versa) with minimal effort.

Whether you need to refresh your RM4 or you to alter the FPS on your RM4 CQB, you can definitely consider this a must-have.