https://www.sightmark.com/collections/boresights
Boresights for Hunting & Target Shooting | Sightmark
Sightmark's Boresight is ideal for quickly sighting in 9mm Luger pistols, recommended by NTOA for quick draw drills, and includes a carrying case.
for huntingtarget shootingboresightssightmark
https://www.maritime.org/doc/boresight/index.php
Boresights and Boresight Telescopes
boresightstelescopes