The Cell is the most technologically advanced Knee Protection System available. Several patented revolutionary design concepts come together in unison to create this System. The ability to be totally adjustable yet remain rigid, along with a superior fastening design, a natural free-motion hinge, a full coverage knee cup, a pair of undersleeves and Anti-Rotation tethers included in every box make this product stand apart from the other brands. Undersleeves included. Sizing: To ensure proper fit, circumference measurements should be taken directly on the skin with the leg straightened, using a soft tape measure. If a soft tape measure is not available, a piece of string or yarn may be used to calibrate the leg"s diameter, then measured against a hard tape measure. How to measure: Locate the middle of the kneecap and measure around the leg. Measurements should be taken directly on the skin with a straight leg. Sizing: Small - 13-13 7/8" Medium - 14-14 7/8" Large - 15-15 7/8" X-Large 16-16 7/8" XX-Large 17-17 7/8" KTMWorld note: If you are on the upper end of a size"s measurement, you may want to go ahead and get the next size up. Weight: 1.6 lb