This is no longer available, but I found this!
Rechargeable Heated Massaging Stadium Seat
This is the heating and massaging seat cushion that keeps you comfortable at a sporting event or on a camping trip.
The seat has an attached control tab that enables you to select—simultaneously or independently—one of three heat settings up to 115° F on the seat’s back and bottom, and operate one of three vibrating massages that target your back.
Covered in water-resistant nylon, the seat has a soft, comfortable padding, and it folds to just 4″ thick for easy transport using the built-in carrying handle. With quick-adjust support straps for convenient sizing, reinforced corners and edges, and an exterior pocket. Its rechargeable battery provides up to five hours of heat or two hours of heat and massage from a 2-3-hour charge with the included AC adapter.
Supports up to 250 lbs.
Check out the Rechargeable Heated Massaging Stadium Seat
Warmth and a massage sounds wonderful and is sure to help your back.