SatShooter Precision Compass & Angle Finder (Clinometer) Combination Tool Highly accurate  improves accuracy by up to 100%. Precise readings in seconds, decreases installation time by as much as 35% Durable aluminum housing-protects against impact, corrosion and water. Edges at 90 degree angles for contact measuring. Adjustable alignment lenses for maximum clarity. Liquid filled for quick stability in seconds  the liquid will not freeze even in cold weather. Jeweled bearing on both meters for smoothest rotation possible. Durable carrying case and neck lanyard provided. Pocket-size convenience. Use in conjunction with the receiver to accurately identify the satellite position.