BudsGunShop.com - Fixed vs 3 Dot Adj Sights

Robert,you can't knock them loose, knock them out of alignment, snag your clothes on them or damage them. They also many times offer a better sight picture. In the H&K's case, it reduces the size of the top strap, making the gun a bit sleeker.

less expensive, less likely to be "knocked" out of alignment, many types of adjustable sights have more square edges that could hang up on clothing if carrying the gun