Car Seatback Trash Bag Hooks

I like to keep my car clean, and I've found the best spot for me to put a stray wrapper or empty can or cup while I'm piloting the scow is in a bag behind the passenger's seat. I used to have a reuseable bag in my VW Beetle that I'd throw stuff in, but to empty it, you'd have to take the seat cushion up and off... which in a Beetle means sliding the seat all the way back, then tipping it all the way forward... with a full bag of trash.
These hooks snap onto the 17mm diameter uprights of my seat cushion in my Ford and drape over the back of the seat to hold a standard plastic bag, or a small reuseable. It's not the most amazing aesthetic solution ever, but it does keep it classy in my ride.