Hi, Thompson. A slow-cooker liner is a tough bag of some clear, synthetic material that withstands high heat. that you put in the slow cooker to keep food from getting cooked on to the ceramic. It saves a lot of scrubbing.

It is made by Reynolds, the company which makes aluminum foil and Reynolds Oven Bags.
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when my mother-in-law turned 70, she announced that she was not going to cook anymore. She had cooked for 50 years and was sick of it. I didn't want to follow her example, so I asked myself how I could make cooking more fun.

I decided that I like cooking but dislike cleaning up, so I decided to buy four things:

Reynolds Oven Bags
Reynolds Slow Cooker bags
parchment paper to put under roasting meats
disposable gloves for handling icky things.

I don't often use the gloves, but occasionally they are truly worth it. For example when yanking the purple gobbets out of a raw chicken.

If anybody comments that I am using up natural resources, I can tell them that I drive an 11-year-old car, I have no television, no cable, no boat...on balance I figure I can spoil myself a little.

Another thing I did is buy two cartons of Rubbermaid storage boxes. They stack nicely and are tough.