New for 2017. This is the last flip cap you will ever need! Virtually indestructible, this cap will fit snugly on nearly all Vortex Optics and features a snap flat spring that will keep your line of sight unobstructed. Product Specifications Outside diameter: 28.25 -31.25 mm | 1.1-1.2 inches OBJECTIVE-24 FITS: RAZOR HD GEN II: RZR-16003, RZR-16004, RZR-16005 VIPER PST : PST-14ST-M, PST-14ST-A, PST-43111 STRIKE EAGLE : SR-1624-1 CROSSFIRE II 30MM: CF2-31037 CROSSFIRE II 1IN: CF2-31047