EdGi Custom Works 13mm Modular Spring 2.3 joules (VSR, SRS, TAC, SSG)This is an EdGi heat treated 13mm spring, custom made by EdGi Custom Works! This is a modular spring, as it works with multiple bolt action platforms, due to it being a 13mm spring and how the spring is designed. Compatibility VSR 10 compatible with a 9mm spring guide Works with Springer Customs (with sleeve), Sniper Mechanics, or any 7mm spring guide with sleeve Modular ex: VSR 10, Silverback SRS A1 A2, Silverback TAC 41, Novritsch SSG10, AAC T10 T11