This is what you need if you wish to use your airgun with open sights. It is fixed by a plastic grub screw, so it will not mark the surface. This rear sight is 64 mm (2.5") long can be mounted on dovetail or picatinny rail (please, choose the right option for you). It is fully adjustable for both elevation and windage (fine adjustment). Made of 3D printed strong black plastic and has super bright fibre optics, which helps the aiming a lot.

Very easy to fit.

Note to ebay: This item is an accessory for a BB Gun, Pellet Gun or Air Rifle. It's NOT a firearm part or accessory & won't fit any type of firearm.