The magnetic base in the rifle level bridges the bolt raceway, allowing you to position your rifle almost perfectly level. Then level the scope, tighten the rings and the job is done. The simplest, most accurate scope leveling system ever devised to level your scope as you mount it on your rifle. The magnetic base in the rifle level bridges the bolt raceway, allowing you to position your rifle almost perfectly level. Then level the scope, tighten the rings and the job is done. Works with practically any bolt-action rifle. Set includes two levels.