The sizing of the calf strap is misleading. I called Sportaid and was instructed to simply choose the width of my wheelchair for the size. But as you know, some wheelchairs have narrower footplates and front rigging (frame holding footrest) than others. I followed Sportaid's advice and ordered the size based on wheelchair width, and the strap I received is much too wide for my front rigging and overlaps so much the velcro is almost totally out of range. Beware!