This is a set of two adhesive-type backrests that came with a straight, large-capacity, box-shaped rear box (top case), which has recently become more common on delivery vehicles like Uber, replacing the traditional curved rear boxes from brands like GIVI and SHAD. These backrests were included with the purchase of a 65L box-shaped rear box. While I installed the box on my bike, I didn't need the backrests since I don't ride tandem, so I kept them in storage without installing them. These box-type rear boxes are sold by various overseas manufacturers in sizes ranging from 45L to 55L, 58L, 60L, 65L, 80L, and 100L. However, these backrests are universal and can be installed on any size box. These backrests provide comfortable support with high cushioning for the back of the passenger during tandem riding on touring trips, or for leaning against during breaks while making Uber deliveries, making long rides more comfortable. Are these suitable for those who didn't receive them when they purchased their new box? - Upper backrest size: Width 14cm, Height 10cm, Thickness 3.5cm - Lower backrest size: Width 27cm, Height 15cm, Thickness 3cm