This Lyman manufactured No. 48 receiver peep sight is for the U.S. model 1917 Enfield bolt action rifle. This sight has the removeable 5/8" eye cup (aperture), target knobs and is marked "RS" on the base portion. The sight is the third variation featuring the scalloped cut on the inside of the base so that the stock will not require cutting. The overall condition is very good exhibiting most of its original blue finish with light wear. The mounting screws are included along with the original black two piece cardboard box. Your rifle may require drilling and tapping to install.