Gehmann Redfield/Parker-Hale Rear Sight Iris .5-3.0mm PH510 Gehmann rearsight iris for use with Parker-Hale or Redfield Much shorter and adjustable over a wider range of 0.5 - 3.0mm The fixed-seat iris works with individually pin-located tempered spring steel leaves The aim-point is precisely maintained through the wider range of adjustment by the introduction of a new system of aperture control operated by varying the pressure of a steel tube against the central aiming ring this guarantees a perfect circle at any point within the scale Light reflection is kept to a minimum by external and internal matte finishes Gehmann patented so not available in other manufacturers' irises Laser engraved indications For use with Parker-Hale or Redfield Thread W 7/32"x40Gg Black