What are they, where can I find them, and how much?
Ameriglo Hack sights Model GL-433. $72+ shipping. AmeriGlo Weapon Sights | Special Combinations
So you like the all black rear sights?
Definitely. The 3 dot setup was just too busy for me and was kind of distracting. These work much better for me.
The best thing about them is the tritium/painted front sight. The red really pops out during the day and it functions as a normal night sight in the dark.