This is a set of US10 and US20. The straps for fixing to the motorcycle are missing. If you want to fix it to the tandem seat, you will need to purchase the following separately: https://store.shopping.yahoo.co.jp/webike02/24639474.html or something like this: https://www.kriega.jp/product-page/%E3%82%B5%E3%83%96%E3%83%95%E3%83%AC%E3%83%BC%E3%83%A0%E3%83%AB%E3%83%BC%E3%83%97