TPU CONSTRUCTION: TPU Covers are smooth to the touch, flexible, yet extremely durable and strong. SPINAL CORD HOLDERS: Flexible elastic cords in the spine can be used to hold extra stapled, spiral, or hard cover books. CLOSURE: Tough webbing closure strap keeps all of the cover’s contents firmly secured. CARD HOLDER: Inside the cover are two card slots, each slot comfortably fits 2 cards. INSIDE STORAGE: Slim interior pockets open toward the spine to keep folded sheets, pouches, receipts, and your cell phone safe from the elements or from accidentally slipping out. PEN HOLDERS: Three elastic pen holders located on the exterior and interior of the cover keep your writing utensils and plant tags close at hand. SPINE LOOP: Handy webbed loop on the spine allows for easy removal from a pack or hanging on a lanyard.