Feature A 100% avoid CANT, Designed for Real Fire Calibers & Long Range Shooting, 30mm Diameter w/ 1" Adapter A Easy to Use, Air Bubble Level, Angle Indicator on Side, Designed for Real Firearms, Full Metal, See-through A This ADI is calibrated in degrees and cosines give you an instant read out which can enter directly into ballistic software program on your pocket PC or use with a pre-printed angle drop chart to achieve high accurate shooting.The red needle moves with your rifle and displays a number that indicates the percent your rifle is off level. Multiply the indicated percent by the target distance to easily calculate the adjusted distance for gravity.The bubble level which can be flipped to the side also allows you to have an additional indicator to achieve much higher accuracy. Picture Specification A Diameter:30mm with 1" adapter A Length:73mm (2.9 inch) A Ring Width:14mm (0.5 inch) A Indicator Dia.:30mm (1.2 inch) A Weight:62g (2.2 ounce) A Finish:Black matte A Angle indicator and scope level support long range precision shooting A Designed for real fire arms A The bubble level can be put on either side A See-through style A Level and indicator were both center aligned during the assembling A High quality 6063 T6 aircraft grade aluminum alloy A Including items: hex key, 25.4mm 1" adapter Ps:1, If not satisfied with the angle indicator position, use the proper screwdriver to release the indicator screw and reset its position. 2, If the bubble is not shown in the middle or is not vertical when it&';s on the left side, use proper screwdriver to adjust the tiny screw for different height.