This is a AmeriGlo Sight known as the Pro i-Dot, model GL-203.
Single Dot Rear (green tritium" no outline) featuring a .180" rear notch. Rear extends to end of slide and has an under-cut face to eliminate glare. Paired with a tritium front sight (green w/ orange outline.
Features:
Green tritium
.140 wide with orange outline front;Green tritium no outline .180 wide rear notch
