I was in the market for a laser for my carry gun, a sub-compact Springfield XD in .40 caliber. I was looking very hard at the Crimson Trace laser that wraps around the grip. I contacted my local gun dealer about ordering me one and he suggested that I look at the Laserlyte rear sight laser. I had seen that they were availble for Glock pistols and at first thought that they look too cumbersome perched there upon the rear of the slide. I took a gander at the laserlyte sight that only recently come out for the XD. I did my research and looked at reviews on line and at Laserlytes web site also. I bought the laserlyte rear sight laser for about $125.00 less than what was being asked for the Crimson Trace laser. My dealer installed the sight on my pistol. The sights come with tools for installtion and adjustment as well as an extra set of batteries. The batteries are 366 button cells and the sight requires 4 of them. Run time is estimated at 1 hour for laser in constant mode and 2 hours in pulse mode. Installtion is easy, remove the rear sight on the pistol, and put the laserlyte sight in the dove tail. Gently tap the sight into postion with the supplied brass punch and measure to ensure the sight is centered. Me being me when a little is good more is better, so adjustments on the sight need to be done in very small incriments,I learned a lesson there. At first I made adjustments that were too big and the sight was unable to be readjusted to aim the laser at point of aim. After a few rounds I realized that the sight could not be adjusted. The iron sights were dead on and are readily used. I called the company and was instructed to back the set screws alsmost all the way out and the let it set for 1/2 an hour and the sight would return to zero. I did this and viola it returned to the original setting. The company claims the sight is visible at night to 500 yards and I believe that. It has a brilliant red dot that really reaches out there. The sight is well made of steel, and after a while looks not so cumbersome on the pistol. It fits in every holster that I have for the XD and I believe that it will hold up good under most conditions. The web site shows the sight being used to drive a nail into a board. The sight is easily activated with the thumb while gripping the pistol. www.laserlyte.com