Power Tuning Hammer spring for your FX Impact MKI, MKII, M3 and M4 This hammer spring has a bit more higher power curve compared to the genuine FX Impact hammer spring what will give you more flexibility and power adjustment options when using the power wheel of your FX Impact. It’s great when you want to tune your FX impact for slugs or hybrid slugs. Also it makes a perfect combination with our FX Impact Tuning Valve Return Spring
