Review on Hexers RPG Board Mat, Square Grid Terrains (8 Varieties), Compatible With D&D/Pathfinder, 27" X 23", 1" Squares - Foldable & Dry Erase by Charley Prz

Using this for dnd sessions instead of graph paper with poorly drawn lines has saved a bunch of time in combat, not worrying about where the edge of a 5x5 ft square is. However you can get that with any game mat. I bought this one because they were double sided with various textures that I liked on each side, plus they fold instead of roll so they avoid the problem of it trying to roll back up. I highly recommend this if you like the patterns they offer.