What will this be used for, since you are wanting night site I will assume for SD. I have the true glow tfo's and while I do like them my next sites will be trijicons HD. I like these better for self defense, they are made tough and one hand racking of the slide is much easier then with the tfo's.
Here's what I did with my TFO's. there is a slot on the top of the rear sites that lets the light in to be gathered by the light tube. since I want the front site to POP out at me I filled the rear site slots with epoxy. this makes them dark in the daylight, however in very low light the tritium shines thu the tube and you can't tell I did anything to them.