The three 1.5 volt batteries (LR-44) are already installed. To replace batteries you can use LR-44, GPA76, AG13, G14A or A347 batteries. Either a mill collet or drill chuck is required to use the unit.
If you are using a drill chuck, here are some helpful hints on using our tool. Because the jaws of a drill chuck can get badly damaged during use, it is hard to align our tool repeatedly by simply inserting it in the chuck. To help alleviate the problem, when you first align the tool in the drill chuck, place a felt tip mark on both the tool and the drill chuck so that you can put the tool back in the same place each time you use it. This gives you a better chance of keeping it accurate.
Once the Laser Center/Edge Finder ® is installed in the mill, apply thumb pressure, slightly downward, to the black Battery Holder/On-Off switch and rotate in either direction. The white mark should be facing out when it is on. Do not turn upside down and look at the light source. Move the table until the laser light is showing down the edge of the material, or to find a center punch mark, move the table until the light is in the center of the center punch mark. Rotate the polarizer to make the dot smaller until it is in the center of the center punch mark. This is the Direct Method. No more slightly touching the edge of the old center finder and then moving the table an additional amount, the Indirect Method.