Plastic liner...door panels

Now I can't find what I want. Maybe one of you reading this will know. When the door panels are removed, there is also a sheet of clear plastic attached to the door held in place with adhesive. I think most cars have the same plastic as well..keep the water out.
I want to buy some of these plastic door liners. I saw them for sale some months ago and now I can't locate them. Feel free to tell be where I can buy some! I can buy some plastic from home depot...have to do a lot of trimming, etc...rather buy the one that will fit correctly.
Thank you for your help!