Complete, high capacity magazines. TIG welded, heat-treated, stainless steel bodies hold up to competition use without cracking or failure. All springs are tempered music wire, and fit STI bodies without trimming. Complete mags come with Polymer base pad and nylon follower for flawless feeding. Mfg: Sti SPECS: 410 stainless steel tubes. Fits STI, SVI & McCormick high capacity frames only. Capacity shown for all models is with non-extended magazine pads.