Welcome to the Forum neil! I'm sure some of our members will be along shortly to answer your question. Glad you're here. I hope you enjoy the forum.
Welcome to the Glock Forum !! Excuse me for asking...where are the instructions that came with the unit ?
If you don't have a manual hopefully you have the tiny Allen head wrenches included in the kit. There are 2 tiny bolts that look like holes on the sides of the laser projector. One controls the vertical plane the other the horizontal. Turn each until you have them set to where your iron sights point of aim. I have mine set a hair under the top of the front sight at 15 yards.
