ZWQ S400 2.0 Upgrade Spring

ZWQ's 2.0 Upgrade Spring is the manufacturer's own answer for players who want more power out of a stock ZWQ S400. Dropped in as a replacement for the factory main spring, it's rated to push the blaster to roughly 305 FPS on average, a meaningful jump over stock performance for anyone who wants their S400 hitting harder.

Important: spring swaps on the S400 aren't something to rush, and ZWQ specifically flags this 2.0 Spring as one to be extra careful with when installing — take your time and follow proper procedure rather than forcing anything. Beyond the raw FPS gain, it's a good option for players who feel their S400 has plateaued on stock internals and want an official ZWQ-made upgrade rather than a third-party part of unknown quality.