Flatline Ops custom fitting level for MARK4 Leupold 30mm scope mounts. The MARK4 Adapter replaces the top bracket of your existing scope bracket for a custom seamless one-of-a-kind fit. A long-range shot has many factors to take into consideration to be sure you are on target, and the ACCU/LEVEL™ system aids in the correction of "cant error," giving you dead-on true vertical hold. The level also features a dual-position detent locator to make sure you are locked into place before taking that critical shot. Each level is machined from advanced 6061-T6 aircraft aluminum and then black hard anodized to protect it from the extremes of the outdoors. The level is also designed to fit right- or left-handed shooters. High-visibility fluorescent fluid level is easy to visualize and locate before each shot. You also have the ability to make fine adjustments to the level in the open and closed positions.