Sig Sauer Kilo 1600 Sierra 3 BDX Range Finder Rifle Scope Combo Kit. The BDX rangefinder and riflescope system is simple, fast, and intuitive. Simply download the “SIG BDX” app available for Android or iOS smartphones, pair the KILO BDX rangefinder and SIERRA3BDX riflescope, set up a basic ballistic profile, and then you’re ready to shoot or hunt. Once you are in the field, range your target as you normally would, and the KILO BDX rangefinder will utilize onboard Applied Ballistics Ultralight™ to instantly send your dope to the scope via Bluetooth.