PG Power Grips provide a hands-free, easy exit way to increased power for all levels of mountain bike, road and recumbent riders. No special shoes required. Power Grips Pedal strap set easily attaches to your existing pedals. Fits most metal cage pedals that accept standard toe clips and straps. Comes with all necessary hardware. Includes our micro-adjustable bracket which easily adjusts to fit different shoe sizes with a standard 4mm allen wrench. Size Extra Long straps recommended if the circumference of your shoe around the widest part of your foot is more than 13 inches(simply selectand quot;XL Black" in theand quot;color / Size" box below). Usually this pertains to size 12 and above, but is very dependent on the type of shoes or boots used. How it works Power Grips patented Dynamic Tension design works by combining the natural rotation of your foot with the diagonally positioned strap. As you rotate your foot, the strap naturally tightens and loosens, delivering exactly the amount of grip you desire...and that the terrain requires. CLICK TO ANIMATE Comparison: POWER GRIPS vs. STD vs. Toe Clip Pedals