In Oz we call 'em draft extruders.
What is the name of the thin sausage like shapes that you place against the bottom of a door to stop cold or hot air?
Giraffe excluder
Air trapper or a towel
They are called :Draft Guards. Amazon has a load of them but I'm sure you can get them at any hardware store.
Under Door Draft Stopper (if you have to get descriptive for the clerk.)