This product is designed to clamp to collapsible steering columns to offer added protection for your knees in case of a racing incident. Unlike others, our one of a kind structured material has been designed to be ridgid, yet forgiving under pressure to absorb the impact created by your knees. This structure is wrapped in 1/2 inch fireproof racing foam and then covered with fire retardant fabric. This product offers the strength needed to protect your knees/legs from hitting the steering column or each other, all while being lightweight! This knee knocker is 8” tall, 6 1/2” wide and 2” thick. Hose clamps not included.