LensCovers Wear Over Sunglasses - Rectangle Frame Both Round and Oval faces are ideal for LensCovers Rectangle Wear Over Frames: If your face is nearly as wide as it is long, without a prominent jawline you have a round face. For round faces, rectangular frames help elongate the face, breaking up the face structure, making it appear longer and thinner. An oval face is defined by evenly proportioned features - cheekbones that rest higher than the middle of your face and a chin that is slightly narrower than the width of your forehead. Rectangle frames highlight your cheekbones and make your jaw appear thinner and more angular. How to measure your prescription frames for LensCover sunglasses: 1- Measure the widest part of your prescription frames left to right, this is the "width". Next measure the height of the lens with frame included. 2- Choose the LensCover frame (below) that is slightly larger in width and height than your frame measurements. LensCovers Extra Small is 4-15/16 inches x 1-1/2 inches highLensCovers Small is 5-5/16 inches wide x 1-5/8 inches highLensCovers Medium is 5-1/2 inches wide x 1-3/4 inches high LensCovers Large Slim is 5-11/16 inches wide x 1-7/8 inches highLensCovers Large is 5-3/4 inches wide x 2-1/8 inches high For example, if your prescription frames measure 5-1/4 inches (width) x 1-1/4 inches (height), the correct LensCovers Frame would be size Small. Hard Case for LensCovers are available under a separate listing.