The waterproof map case is for maps and navigation aids. The case is made from a durable 420D nylon fabric with a double sided TPU window to view and protect your maps and paperwork. The IPX7 rated construction prevents the ingression of water, sand and dirt. Insert your belongings into the case, run your thumb and index finger along each side of the two track LocTop closure and shut with the secure fastening. You can either wear the case around your neck using the lanyard or secure it to your gear using the four lash points. These are the waterproof map cases recommended by Ordnance Survey.