Threaded for standard target rearsights colour filter with twin polariserRemovable steel thread allows retro-fitting of our 50309 magnifying diopter (-4.5 to +4.5)Locking collar allows precise location of the V-markLaser engraved indicationsTwo polarisation filters1. ring eliminates glare and controls white round target2. ring (with lugs) controls light through the sightFilters (filter and polariser) can be used together or one at a timeAdjustable iris made to our latest patent covering the range 0.5mm to 3.0mmInternal surfaces are matt black reducing light reflection to a minimumMatt finish to eliminate reflected light and subsequently distortion of the sight pictureSix optically flat glass colour filters which can be precisely located in position, colours: orange, light green, yellow, medium grey, dark grey and amethystClear settings at either end of the adjustment range for use of iris only or polarisation onlyContact us at 70822-33324, if the product is in pre-order status.