I bid on a sight knowing it was a marble-Goss Bolt sleeve sight but didn't know how complete it was or what it fit. It slid right in place of the safety on my springfield.
Kind of lucky that the stem that fits into the safety hole is still with the sight because nothing holds it into the sight, is just a locating pin. A set screw sets into the slot that the safety detent ball rides in, locking the sight to the bolt sleeve.
The spring loaded pin and a set screw on the underside ride up onto the receiver bringing the sight to the same position each time the bolt is closed.
The safety lever on the side turns a notched shaft that would fit into a slot filed into the cocking piece, locking it in place when cocked.