The SME Bubble Level Anti-Cant Device for Picatinny Rails allows the shooter to check both the rifle bore and reticle alignment at a glance. It's constructed of aircraft grade aluminum and attaches to any picatinny or weaver style rail. FeaturesPrecisely level your scope and crosshairsLevel allows the shooter to check both the rifle bore and reticle alignment at a glanceConstructed of aircraft grade aluminumAttaches to any weaver-style rail or baseWhite scribed line on housing for quick referenceHex wrench for mounting included