GlobalPioneer Tactical Brass Crossbow Archery Arrow Red Laser Bore Sighter Tool Threads onto Arrows (Batteries Included) Arrow laser sighting tool for compund bows, cross-bows and all thread bows. Laser unit fits directly on to the arrow,No More Losing or Damaging Arrows. Simply place batteries in end cap twist end cap to turn on and place in chamber,Easy to use. Arrow Laser Aiming Device with Batteries Included. The battery lasts about 10 minutes Class IIIa 635nM Less Than 5mW, Avoid Direct Eye Exposure to Beam. Battery: 3*LR-41; Weight: 0.9 oz.