STAEDTLER Lumo Color Whiteboard Marker Square Tip 6-Piece Set(Black, Blue, Red, Green, Orange, Purple).The pen uses "Dry Safe Ink" that protects the pen tip from drying out, so the pen tip will not dry out even if the cap is open for three days (ISO 554). The square tip makes it easy to write thick letters. Line width: 2-5 mm. It comes with a special case that can be used as a pen stand, making it convenient to store and carry around.Refillable,oily ink,square core pen tip/nip