Tru Level Picatinny 10/22 Scope BaseStops Canting and Improves Accuracy This Ruger 10/22 Picatinny Scope Base has an integral level tube that you can see beneath the eyepiece when aiming a riflescope. By keeping the bubble in the middle, you stop "canting" your rifle from side to side... And, you end up shooting more accurately. The scope base itself is Weaver style and Picatinny compatible with extra length to compensate for just about any special eye relief needs.