Legamaster Separation tape Black Width 2.5mm, 16 m for clear and easy lines on whiteboards or glassboards removeable whiteboard

Amazon

Self adhesive divider tape is a quick and precise way of marking out columns and rows to transform any whiteboard into a planner Handy dispenser for easy application Tape can be removed and board re-used Available in black colour Measures 16 metres length by 2.5mm width

Euroffice

Tape for planning boards. Mark out columns and rows on a whiteboard. Includes dispenser for quick application. Self-adhesive backing. Remove and reuse tape easily. Colour: Black. 2.5mm wide tape on 16m roll.