Hs403a vs. hs403gl - Holosun Paralow HS403B 1x20mm 2 MOA Red Dot Sight

I bought the HS403A for the slightly smaller profile when looking down the optic as compared to the HS403GL, but exchanged it for the GL after seeing the batter cover in person. Basically, the battery on the HS403A goes between the red dot and the mount, under a rubber flap that you lift up, then essentially an electrode that you slide the battery under. So the battery is sandwiched between the negative electrode on the optic side, and the positive electrode/terminal and rubber flap on the other, and the whole thing is screwed onto the mount which pressed the rubber flap against the optic and (hopefully) creates a water-tight seal. That is, the rubber cover/flap does not lock into place, itself, but relies on the red dot being securely tightened to the mount for a water-tight seal. That was just a little too unnerving for me. I'll admit that I don't expect my rifle to ever be submerged and I don't think it would ever be a risk of water entering the battery compartment, even if it was rained on.

I'm VERY happy with the HS403GL. It's compact, seems to hold zero pretty well (I've only shot it a couple times, but haven't noticed any drift in the point of contact relative to the red dot yet), and looks pretty cool. As others have said, the dot isn't crisp, but that doesn't bother me for my purposes. I don't actually shoot much so am not the best shot, but I had decent groupings (didn't think to measure) at 50 yards.

I had both red dots briefly so was able to compare them side by side. Other than the battery compartment, both the HS403A and GL seem to be nearly identical. The lens coating is the same, same dimensions, approximate same weight, same dot clarity/brightness and settings, and both seemed to be built tough enough to take a beating (with the exception of the battery compartment of the HS403A). Maybe if you're an avid shooter/hunter/LEO you might want to fork out the extra money for AimPoint, EOtech, or Trijicon but, otherwise, you really can't go wrong with Holosun!