14 Inch x 14 Inch Vent (Rough opening of 14.25" X 14.25") with Radius Corners. Lift mechanism provides a smooth operation and eliminates chatter. The slide mechanism has more surface area contact. Making the guide bar stronger and allowing better distribution of stress. 2-piece snap-out screen easily detaches for cleaning. The ceiling garnish and crank handle remain in place: no screws to lose. Easy-grip knob operator replaces the traditional L-shaped crank handle and allows for a smoother operation of the lift assembly. The knob also detaches easily. Permitting faster screen removal and cleaning. The knob is interchangeable with the L-shaped crank. So you can also use it on older vents. Polypropylene dome models feature aerodynamically wedge-shaped dome that has 4 times the impact strength of other polypropylene covers on the market. Be sure to install with the hinge side of the vent facing the front of the RV. 14.25 inch x 14.25 inch rough opening. Extra strong Galvanized steel roof flanges. Flange is very sharp, Be sure to wear gloves and handle carefully! Non-powered vent. Bright White lid; includes 1.25 inch White garnish. MOUNTING HARDWARE AND SCREWS ARE NOT INCLUDED!