Thousands of hours of testing and three years in development have gone into the S1 Pro Knee Pads and they have produced one of the finest knee pads out there today. Comfort, durability, stability and function were at the forefront of the designers minds and now their vision is a reality. S1 Helmet Co are an independently owned and operated brand that is deeply rooted in the Californian skateboarding, longboarding, BMX and roller derby scenes. S1 Helmet Co has an extensive line of protective helmets that are rapidly becoming known throughout the industry, thanks to their unrelenting approach to style and safety, which they have applied not only to their Lifer and Mini Lifer helmets but to their range of Pro Knee Pads. Features: Streamlined pad design Military grade ballistic nylon for durability Articulated butterfly back flaps for secure fit Locking adjustment straps are the perfect length Specification: Impact absorbing knee cup Ortholite memory foam Replaceable PC knee caps Triple stitch construction for extra strength Sizing Info: Measure 4\" above and below from the centre of the knee to find your measurement. SizeTop StrapBottom Strap Small: 11\" - 13\" 9\" - 11\" Medium: 13\" - 15\" 11\" - 13\" Large: 15\" - 17\" 13\" - 15\" X-Large: 17\" - 19\" 15\" - 17\" S1 recommend going a size up if you find yourself at the top of the size bracket as their pad sizes run just a little small.