These "Eagle Eyes" are a magnifying lens that fits into the front of your foresight tunnel. They magnify the target area by 0.3X or 0.5X. For smallbore you may find the 0.5X a bit much so see how you get on with the 0.3X. They are now legal under NSRA rules. Because they magnify the target you may find you have to increase the size of your foresight element to get the same sight picture. A rough guide is about 0.60mm increase for the 0.3X and about 1.00mm for the 0.5X. Don't forget to keep them very clean because they will attract dust, dirt and water.