Green laser - SightMark LoPro Mini Laser Sight

This sight looks neat but doesn't hold zero with a 308 AR. I have used this to get close to zero for scope swaps (zero it in on the known good scope at 100 yards, then set the new scope to match the green dot). But the mount itself it tight, but a single shot from the 308 throws the zero off by 18". Not something I would rely on to use in any real situation.