MagTracker

This is a part to find the center of a round apliancebox "eldosa" through an osb or a gypsom/sheetrock board.

needs two nedymium magnets 16mm diameter

the main body is about the size of a regular apliancebox in the EU/Sweden (apparatdosa)
and the frame make it fit an apliancebox of the bigger kind (kopplingsdosa)

there are a similar commercial version of this called Hole-In-One they are better but expensive