Comes with ADE RD3-028 Ares red dot, a mounting plate for certain HK USP pistol models, and also a standard picatinny mount. While it is possible to install this mount without the use of a gunsmith, we recommend hiring a qualified gunsmith. Unprofessional installation will result in screw loose, not holding zero, damage to the firearm/optic and personal injury. The HK USP dovetail has two popular width, one is 12mm, another size is 10mm. This plate fits 12mm dovetail, it does NOT fit the 10mm dovetail unless you grind/file it. Please MEASURE before purchasing. Below is a list of HK USP models come with both size 10mm and 12mm dovetails. HK made the different sizes over different production run. Need to confirm before purchasing. USP Tactical 9mm (need to check dovetail size). (need to check dovetail size). The mount for HK does not fit. USP Compact rear sight cut depth is. You will receive the reply within 8 hours Monday-Sunday. When you first receive the ADE red dot. It might have a picatinny mounting plate pre-assembled (might be packaged separately in the retail package, depending on the ADE model). Please use the allen wrench provided to take out the 2 hex screws on the top behind the glass frame. It will disconnect the red dot from the picatinny mounting plate. ADE is releasing the 2023 PRO SERIES for ADE RD3 series that fits a varieties of popular optic footprint on the market. The additional features that the PRO series includes are Multi Reticle Technology(only on select models, read product description to see if this model is equipped), Motion Awake System and are a new cosmetic redesign by ADE in Oregon City, Oregon. ADE RD3-028 Ares Pro is equipped with the Motion Activated System. While the Ares Pro is turned on, the red dot illumination goes to sleep after five minutes of inactivity, but when any motion or vibration is detected, it instantly switches on illumination at the previous brightness setting. Users also have the option to manually turn the red dot power off to disable the Motion Activated System. The overall length is longer than traditional red dot, therefore it only fits on the optic plate that sits ABOVE the slide(typically the plates replacing the rear sight). It does not sit into pistol slide with a milled optic cut because those cuts are typically made for red dots with standard length. The dimension for Ares is 1.84″ length x1.30″ width x1.15 height. ADE RD3-028 Ares Pro is designed with a removeable Weather Shield that protects the sight from moisture and provides a clearer sight picture during inclement weather. Once installed the weather shield will protect from rain or snow and will stay attached even when mounted on a handgun. Promotes rapid target acquisition while providing a precise point of aim; getting shots down range and on target fast. Side Battery Load System, no need to Remove the sight to change the Battery. 3.5MOA red dot. Fully windage and elevation adjustable and lockable; Unlimited Eye Relief. Powered by a lithium CR2032. Comes with a removeable picatinny plate, lens cloth, instruction, tool, battery and a removeable weather shield. We always reply emails within 8 hours. All NFA rules apply, where applicable. YOU are responsible to following ALL laws and regulations regarding the ownership, possession and end use of this item.