Check the listing for details. For Nerf Rival Kronos Blaster K25 Coil Spring Easy Prime Mod Upgrade High Power. Condition: New. Listed at 5.49 USD. ***** SPRING ONLY! (Blaster Not Included)***** New! Rival Kronos Easy Prime K25 High Power Coil Spring! Newly Cut K25 Spring with Ground down Smooth Rounded Ends. This is a tested and verified N. Rival Kronos Spring Upgrade. The K25 Kronos Spring is a significant spring upgrade over the stock spring that comes in the Kronos.It is a little weaker than the K26 Spring, but it is much easier to Prime. 20% + Increase in Power and Distance! *This spring is a tight fit. Some modding skills are required to make it work. For use: In replacements in the N. Rival Kronos Blaster K25 Spring Measured and Tested for optimal use in a Kronos Blaster! Compression Spring - Spring Tempered Steel This mod will make your blaster more powerful. Use at your own risk.