FN 509 Tactical 

It's actually good and holds zero good. Only issue I've had is the rear sight on the fn blocks the adjustments for the red dot on the vortex viper.

@@ITZ_DADDYSON how regularly do you have to change the battery?? because i plan on buying it soon

I've have it now for about a year and not changed it. It's said 150 hours on the highest setting and 30,000 hours on the lowest. Probably wouldn't hurt if you plan to carry to change it once a year. Inexpensive preventive maintenance! The iron sights Co witness so you'll always have those to fall back on also.