Gehmann 520B-35mm Iris 4.0-6.0mm Foresight threaded 1¼" x 28 fit The Rightsight

Gehmann #520B-35 Iris foresight

threaded 1 ¼" x 28, appears as a perspex element

Fits art. no. 529 big bore foresight unit “Rightsight” 
Infinitely adjustable iris 
With crosshair
520B-35 adjustment range: 4.0 – 6.0mm