Simply attach both of the large spring clips to the board's frame profile, hook the tray in the leather loops, and there you have a broad tray for your Neuland markers.
Technical details:
Aluminum tray, powder-coated in black, structure
Steel clips, black
Leather loop, black, with Neuland embossing
Dimensions: W 71 x D 10 cm / W 28 x D 3.9 inches
