M145 spring for VSR style sniper rifles, will fit AirsoftPro Tokyo Marui VSR rifle and clone upgrade kits. This spring will give your rifle 480-495fps in power depending on other upgrades.
External Diameter 13mm (approximately)
Internal Diameter 10mm (approximately)
All stated powers are approximate and vary hugely depending on other upgrades, age of rifle, barrel length and hop rubber etc. We recommend getting your rifle chronoed before you go to a site.