Magnetic line of force demonstration set rvfm p05009 p align left this magnetic line of force demonstration set is a deluxe 3 d set featuring 2 plastic viewers containing over 200 miniature compasses each each large viewer is 8in 20cm in height and contain a removable side panel for placement of the included magnets easy to use and perfect for dramatically illustrating magnetic lines of force to students p rvfm magnetic line of force demonstration set