Each unit factory calibrated to within +/- 0.25% accuracy. Ideal for firearms, archery, airgun and paintball. Simple operation, large LCD screen. Meters Per Second (MPS) or Feet Per Second (FPS) readings. Extra wide sun screens for added shading in full sun operation. Smart phone interface via included audio jack cable. Displays velocity, logs data, notes, weather conditions, easily exports via SMS or Email. Carry bag included.