Take the guesswork out of mountainous distances with this ACI which helps you calculate the distance to your target and is corrected for gravity. This Sniper Tools Design Company civilian angle cosine indicator is vault solid, water resistant, and made from aircraft grade aluminum with an anodized flat black finish. The numbers are laser engraved in 5 degree increments. The lens is shatterproof and shockproof. No batteries are required. Left hand.