Write ,Delete ,Repeat, Without Damaging Documents.No Wear Or Tear ! Revolutionary Metamocolor Ink Technology - Thermo-Sensitive Gel Ink Disappears With Friction Using Rubber Tail Plug On The Pen,With No Debris (Ink Disappears At About 60C And Recovering Temperature Is Around -10C ).Frixion Ball Can Write Repeatedly On The Same Spot With The Same Pen.Rubberized Grip To Ensure Comfortable Writing.Ideal For Sudoku,Puzzles, Crosswords And Everyday Writing.Available With Medium Point In 8 Colours(Bl,Bk,Rd,Gr,Pink,Torquise Blue & Orange)Strickly Not Recomended For Signatures,Examination Papers,Cheques Or Official Documents Where Writing Needs To Be Of A Permanent Nature.