The Flex board shorts have been tested like no other shorts we have done. We wanted to create a pair of shorts that you can use as fight shorts or in t he gym. After all the tests, we now make them in a lightweight strong polye ster, flexible polyamide fabric in crotch, inside legs and also flexible i n the back, just below waist. High slits in the side seam, three needle, ext ra strong stitching. Velcro and drawstring in waist. MMA: Slits in the side seam, elastic fabric in the crotch and in the back. Inside pocket for yourm outh guard. Perfect for crazy submissions or those "lights out" high kicks . Works as well in the fight gym as in the weight room. GYM: The extra flex ibility is perfect even for heavy leg days. Not to mention, people will thin k twice before cutting you of at the weight rack.