The garmin xero a1 auto-ranging digital bow sight is a led sight with built-in rangefinding capability, the xero a1 sets the pin for an angle-compensated distance to your target up to 100 yards away (300 for reflective targets).Eliminating the estimating needed for angled shots and in-between distances, the system also lets you see your target, unobstructed by the physical pins found on a traditional bow sight.Vhunters choose red or green led pin color and preferred pin setup, offering single pin, multiple pins or manual pin selection.The led pins automatically adjust brightness to conditions.The xero a1i also allows you to save pin settings for various bow configurations.Saves data from shots, such as bow level at release, bow impulse duration and more.The design also works with garmin's laser locate feature on compatible garmin gps devices.Uses 2 aaa lithium batteries (not included).Pin size: red:.007" and above, green:.009" and above.