Fits the LR44 battery perfectly as long as you have the orientation correct. This model doesn't fit my Neiko 6" metal caliper like the title suggests. The width of the body of the "brains" doesn't match the opening. Guess I'll try to sand it down, feels like a waste of a 4 hour print though. This is as far as it would fall into the opening. Just over a half of an inch (14.5mm) Another angle of the non matching width.