For those of you frustrated with Ziploc-style closures, here's a map case for you. It boasts a fully waterproof zipper (like on a drysuit) with a big, easy-grab t-grip pull. The case is made with RF welded seams, is electronic device friendly, viewable on both sides, and handles hot and cold temperatures. Four sturdy D-rings at the corners are made to attach the case to your deck or pack. 

Viewable dimensions: 42 x 33 cm