I have two units, one on a small frame revolver and one on a small auto (PPK-S).
They work great and very bright, due to the offset from the bore I set them to be on target at 20 ft. I dont think it's a problem for short ranges but for longer ranges the points diverge.
I have a laser (not C.T.) in my Sig P220 that takes the place of the recoil spring guide and as it is in line with the bore (just a bit lower) it works over a greater range.
Oh buy the way, cats love chaseing the red dot around
PS
I like the fact that I can fire at a target without looking like I'm aiming, in some situations hitting a 10 ring with the weapon in your lap could come in handy.