I have installed both Trijicon and Meprolight sights on my two Glocks (a 27 and 17). They both are excellent. I think that I paid around $90.00-$100.00 for each pair. I did have a gunsmith install them. The glass containing the gas can be fragile, and if you hammer on the sight, they can break. A Glock sight drift tool may be the best bet if you are doing this yourself. Good Luck