Review: I ordered a LaserMax Guide Rod Laser for my Glock 19 from Amazon.com. Today, I received it. It was very easy to put in my weapon and worked as described when I tested it at home. Off to the range with 300 rounds of Winchester White Box 9mm ammo. At the range, I located my target at 25" from me and began to shoot. The first shot was straight on but low about 1". As I further shot, I noticed my shots moving low and to the left. Some as far as 2-3" from point of aim. Then at around round number 45, the laser stopped working altogether. No beam no matter which way I pushed the switch. After clearing the weapon, I removed the guide rod laser and placed it back in the slide. I reassembled the weapon and ....nothing. It had stopped working and I could not resurrect it. Needless to say, I was disappointed and dismayed. My over $300 laser was worthless. And, I could not continue my shooting session because I left the OEM guide rod at home. As soon as I got home, I proceeded to return it to Amazon.com. No, I did not want a replacement. I wanted my money back. I spent over $300 for this laser and the frustration is not worth repeating.