The traditional standard prism mounting rail system requires to have the scope rail drilled from the side for fixture screws. The more recent proprietary systems mainly offer aesthetic advantages for people who have problems with redundant drill holes in sight in case the riflescope is used on different guns. To avoid drilling the scope rail, the proprietary rail mounting systems have special shape connections machined in the inside of the rail. These shape connections prevent ever showing any exterior damage from mounting work on the rifle scope. The proprietary rail systems use matching slide-in mount fasteners to connect the rifle scope to the gun. Some proprietary rails also offer the possibility to tilt the scope up to 1° (60 moa; 17.5 mrad) to the left or right.