http://www.texasguntalk.com/forums/...arry/21604-trijicon-rmr-review-tsd-glock.html
"For those not familiar with the Trijicon RMR, it's a small "red dot" optic for your handgun, and/or other applications that require compactness and lightweight solutions. The dual illuminated model does not require batteries to operate since it relies upon Trijicon's fiber optic lighting source for daytime and a tritium source for night time; a feature I find absolutely necessary in regards to optics on defensive handguns. It's available in a 4 MOA to 8 MOA dot, the latter being superior for handguns. The model I tested was a 8 MOA dot, which I found to be fast in acquisition and sufficient for repeatable and accurate shot placement."