I just wanted to post a picture of this cooler I received for Christmas. It looks like it will fit nicely on the pillion as well as it straps on top of my panniers if I am riding two up. It is supposed to be waterproof, and is insulated. Costco has these for under $60. It looks to be of comparable quality as the “abominable snowman” brand. I like that I can use it as luggage on my bike as well as other activities off the bike.