Horus Vision ASLI (Angle Slope Level Indicator) with 30mm to 34mm attachment ring mount Magnetically dampened to quickly halt oscillation for fast readings Clear, large numbers for better visibility in low light Readings in both vertical angle degrees and its corresponding cosine value Versatile mounting for left, right, bubble up or upside down, and high angle grenade launching Easy to paint plastic housing to blend ASLI into your scope and gun Tested to withstand the repeated G-shock pounding of a 50cal BMG Attaches to 30mm or 34mm scope tube