Zebra Mckie Double Ended Bold Permanent Marker 2mm and 6mm Line (Pack 10) The Zebra McKie Bold is a double ended permanent marker which is equipped with a 6 mm felt chisel tip and 2 mm acrylic nib allowing for a more even distribution of ink. It uses a low odour oil-based ink that is Xylene/Toluene free which can write on a variety of different surfaces.