I wanted replacement sights for the crappy plastic ones that came on my Walther PDP (I thought only Glock put on cheap plastic crappy sights...), and was pleased to find out that any sights that fit the Glock 19 would fit the PDP. I have TruGlo sights on ALL my pistols so I knew what I was getting, but these were my first Tritium AND fiber-optic all-in-one sights, and I can tell you I am even more impressed than I thought I would be!The Tritium is perfectly bright at night, and by day or indoors in the light, the fiber optics pick up light and make them sights glow nich and bright, so they are great for low light/no light as well as bright light! In fact, in the sun, they are so bright you don't have ANY problem seeing the sight picture! I'm not an 'optics' (red dot) guy, I don't believe in all that garbage for a self-defense weapon, I train and get used to standard, or 'iron' sights, and maintain my proficiency without relying on toys mounted to my pistol.Like I said, I got this model for my Walther PDP as they fit the Glock 19, so if you use THIS set, you will need the Glock front sight tool (you can get that here on Amazon), and a rear-sight press, also from Amazon, both for what it would cost you to pay a gunsmith to do it for you. It takes about ten minutes from start to finish with the correct tools I mentioned above. Please note, do NOT use the red Loctite when installing the screw on the front sight, use the BLUE Loctite, and also USE THE SMALLER SCREW that comes in the package for these sights if installing on a Glock AND for installing on the PDP if that's what you are putting them on...I used the original screw that came on my PDP but the front sight was loose as the PDP screw was too long.I have put about 400 rounds through the PDP so far and the sights are still tight and working as they should. Highly recommend TruGlo...they are as good as the other brands but cost less than most.