The Nightforce Top Ring Replacement with Bubble Level was designed to replace the top half of standard Nightforce mounting rings. By swapping out your standard rings for this replacement, you gain the ability to level your scope with deadly accuracy. These Nightforce Top Ring Replacements are available in six different models for 30-millimeter and 34-millimeter diameter tubes. Each size comes with two options - the bubble level alone or the addition of an integral Angle Degree Indicator (ADI) mount. These Nightforce Top Ring Replacements enable you to further customize your rifle scope in ways that no other company can offer.