SB510 Gehmann rearsight iris, Sauer-Busk threaded

Sauer-Busk threaded
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, which is 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 matt finishes
Gehmann patented, so not available from other manufacturers
Laser engraved indications
Thread M8x0.75