Things I liked: Lens caps, both red and green dots, easy to mount.
Things I would have changed: Not much since it is a $35 sight, but sometimes the top adjustment screw cap gets in the way of turning the brightness knob.
What others should know: It's a really great red dot sight for the price. I have it mounted on my Crosman M4-177, and they make a great combo for plinking!
Things I liked: The weight that it adds to the 2240 pistol, the ability to mount a scope, the stability it adds to the barrel.
Things I would have changed: Better instructions. Other than that, it's perfect.
What others should know: If you own a 2240, I highly recommend this steel breech. The ability to add your own optics is reason enough to buy this.