This sight set uses the Heinie Classic rear design. It is the original rear design produced by Heinie. It has a rear notch width of .125. In addition, this rear sight has the legendary Straight Eight system. One single tritium insert in the rear (for low-light and nighttime shooting) that will aligns vertically with the front sight insert (when used as a set). This vertical alignment is proven to be faster and less confusing for the human eye.
This sight set is for Glock pistols and does not require modifications to the slide. *Melonite Finish*
DISCLAIMER: This product is not manufactured, authorized, endorsed, or warranted by GLOCK.