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. Rifle ranges the world over are littered with broken flip caps. This is one cap you will most likely never see in a flip cap boneyard. The E-10 cap has three stop positions. The first vertical, to put your dope disk (optional accessory) literally right in your face. The second at a 45° and the third at 90° to lay flat back.