The Verifier peep has a lens in it similar to the ones in your reading glasses that will allow you to see your sight pins better on your hunting sight. Don't let changes in your vision compromise your ability to make the shot. The verifier lens sharpens the picture so pins and quarry are easy to see. 1/4" aperture with #7 blue verifier. The 1/4" verifier fits in the 749-42LH and 753-1 peep housings. We recommend use of the 210078 dual hex wrench for inserting verifiers into your peep. See "Where To Buy" on home page for a dealer with a verifier display near you, to help you select the verifier best suited to your needs.