LEVEL5 Standard Drywall Flat Boxes have premium urethane pressure plate seals and beveled edges on the box housings to ensure easy open and close. The pressure plates also open extra wide for easy cleaning. LEVEL5 flat boxes are outfitted with non-marring wheels with durable bearings for ultra-smooth operation. 7 in. and 10 in. versions of the flat boxes also come standard with outsider wheel extensions for use when finishing outside corner beads