1. Easy to Install: Push the sleeve from the head to the direction of the grip, and push the sight from the bottom and upwards. Then you can adjust the sight left and right until the light is at a 90-degree angle to the clubhead.2. The Swing Feel: The sight helps the player to the correct swing feel and can quickly correct the correct hook line, allowing the player to correctly the batting technique.3. Power Supply: The sight is powered by 3 LR44 button batteries. In the "" mode, lasts only 10 seconds. In the "CON" mode, it can continue to emit light until the voltage becomes low and the light becomes weak.Size:5 x 2 x 0.6 inchWeight: about 100gcolor:BlackMaterial:ABS plasticPackage Contents:1 x Golf Swing Sight1 x English instruction manualOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.