The ProMag Sig Sauer P365 365XL 9MM 20 Rd Blue Steel Magazine is a magazine that fits Sig Sauer P365 9mm pistol. The magazine body is constructed of heat treated steel with a black oxide finsih. It features an injection molded magazine follower and the magazine spring is formed from heat treated chrome silicone wire. Fits Sig Sauer P365 9mm pistol Magazine body constructed of heat treated steel with black oxide finish Injection molded magazine follower Magazine spring fromed from heat treated chrome silicone wire Made in the USA