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. Configurations 24- Defender Flip Cap Objective Lens 24 (45.5-48.5 mm) 32 – Outside diameter: 38-41 mm | 1.5-1.6 inches 40 – Outside diameter: 45.5-48.5 mm | 1.8-1.9 inches 44 – Outside diameter: 48-53 mm | 1.89-2.08 inches 50 – Outside diameter: 55-59 mm | 2.2 – 2.3 inches 56- Defender Flip Cap Objective Lens 56 (62-66 mm)