MrChipShoulder,

There is also a transparent 'Crystal' fore-sight tunnel, that is paired with the 'Crystal' iris, to give a more 'ideal' sight picture.

'Current thinking' makes for a rear-sight & iris that are as small as possible, and as transparent to vision as is possible, to mimimise occlusion of vision.

Great emphasis is place on having both eyes open, and both eyes having the same light input. This is said to improve both aiming precision & balance.

The same for the front sight - all leading makers now seem to offer tunnel-less foresights - again for the ideal of the sight picture 'floating' on thin air with no other visual disturbance/occlusion.

Have fun & a good weekend

Best regards

Russ