NOTES FROM LUKE: This precut Nerf N-Strike Elite Strongarm upgrade spring is cut from a K25 and has been tested to match your blaster. This mod is not for young kids! You'll need fairly strong hands to prime this spring as the K25 sits much tighter inside the plunger tube. This spring has been custom cut and tested to fit the Strongarm blaster with an average rating of 100FPS (up 30FPS from the stock average of 70FPS).
FEATURES: -Medium difficulty on installation -One end will be flat/squared, the other will be a raw cut. -100+ FPS average
SPECS: -Cut-to-Length Compression Spring, -Spring-Tempered Steel -Made in the USA of USA steel -75mm Long, hand cut, flat on one end.