Now you can use these dry erase markers on any non-porous surface like your Idiopan or banjira tongue drum. Label the pitch of the note on each tongue to quickly see the pitch of that specfic tongue . SIMPLY THE BEST! - The ONLY liquid chalk markers that come with eraser and magnet built right into the cap! No need to have a separate cloth for cleaning. Compare to competitors and be amazed! This marker makes writing easy, effortless, and fun! No need to worry about chalk dust or wiping the chalk off your hands! PERFECT FOR NON-POROUS SURFACES! To wipe off simply use the marker head eraser or a damp cloth. Be Creative!