I got a Generation 4 model 17 and had the gunshop install the Laserlyte rear sight. It is really cool. The lazer shows up bright indoors, but fades outdoors in bright light. You can still use a flashlight on the rail if you want. You can still use a bayonet on the rail if you want. (OK, OK, I am joking about using the bayonet, although I did buy one for the novelty factor.) If the laser is not bright enough, or the battery is dead, or whatever, you still have the open sights. The Laserlyte does not cause problems with my holsters. I do not carry daily, and have not had the Laserlyte for very long, so I don't know if it will snag on clothes and such, or how well it will hold up over time, or how long the batteries will last.