This is really really cool, and it looks good on a rifle to boot. It gives you the option of having an optic that can operate as a CQC red dot and if the need arises, to switch it to a x4 optic as well.
http://www.botachtactical.com/elcanspecterdr.html
Here it is on a SCAR-17s
Again on an AR15
http://www.botachtactical.com/elcanspecterdr.html
Here it is on a SCAR-17s
Again on an AR15