<b>Instructions:</b> <br> 1. Install battery into the boresighter. Make sure the two position lines are aligned.<br> 2. Choose the proper adapter(insert) that fits the barrel of your firearm.<br> 3. Install the adapter on the small end of the boresighter, then tighten the screw to expand the adapter, and make sure it fit in barrel firmly.<br> 4. Insert the small rod of the boresighter into the barrel of your firearm. Make sure the boresighter is inserted deeply enough to snug with the barrel opening of your firearm.<br> 5. After you press the button, a small red or green dot will be emitted. And then you can adjust your scope windage and elevation so that the crosshair stays on the red or green dot.<br> <br> <b>Warning:</b> <br> <b>Before adjust your scope, make sure that the firearm is unloaded and the muzzle is pointed in a safe direction.</b> <br> <b>After the firearms is adjusted, make sure to remove the boresighter and adapter from the firearm.</b> <br> <b>Keep boresight light beam away from eyes.</b><br> <br> <b>Specifications:</b> <br> Weight: 1.65oz<br> Material: Aluminum.<br> Big end Diameter: 0.8".<br> Small end Diameter: 0.169".<br> Length: 6.57"<br> Shortest barrel available: 1.95".<br> Light Color: Green.<br> Wavelength: 532nm.<br> Max. Output Power: ≤ 4.5mW.<br> Light class: IIIa.<br> Batteries type: CR2 3V 800mAh, non rechargeable.<br> <br> <b>Packing List:</b> <br> 1 x Boresighter <br> 2 x CR2 battery (800mAh each battery) <br>2 sets Adapters (2 packs)<br> 1 x Screwdriver <br> 1 x Instructions <br>