It is a cover that prevents the seat from getting wet when you move between points while riding a car while wearing a wader or when you have to wear a rain suit and drive.The setting method is simple, take out the seat from the storage bag, insert a headrest between the seat and the bag, and buckle the belts attached to the two places behind the seat and it's OK!When used as a seat cover, the storage bag becomes a pocket in the back seat. The size when unfolded:Width 66 cm, length (longest part) 125 cm,Belt length for mounting: 30 cm (+6 cm when stretched because it is rubber)