BURRIS KNOB SYNERGYA(R) ADVANCED CAPPED KNOB The BurrisA(R) Knob Synergy Advanced Capped Elevation Knob is a simple addition to your Burris Fullfield Scope that allows you to dial elevation for a specific distance based on yardage. Dialed distance will vary based on caliber, ammo, and environmental variables. The knob features a laser-marked scale that helps keep track of adjustments for advanced shooters who prefer to dial for distance. The knob also features a resettable, mechanical zero click stop for easy return to zero. This is the capped knob, so it prevents unwanted movement. Note: Some Burris Fullfield Rifle Scopes already come equipped with this Knob, so check your model nu Mfg: Burris