There are twop versions of the CD slot insert:- mount 119 mm w deeper magnet hole.stl is designed to fit 1lss.com's neodym magnet stripe- mount 119 mm w 5x5x15 magnets.stl can hold 4 pcs 5x5x15 mm neodym magnetsAssembly:- pick a magnetic phone case (idea came from http://1lss.com/pages/iphone)- push magnets into this CD slot insert and close it with the lock- push the CD slot insert to the car's CD slot