Membrane blanket

Provided by the ASK Keyboard Dictionary

Aka/also known as: rubber mat, rubber sheet

The membrane blanket (or simply blanket) is a sheet of rubbery material found inside Model M keyboard assemblies that dampen the stress the keyboard's actuators (such as the pivot plates on buckling spring keyboards) exert on the membrane assembly. Without it, a Unicomp employee has stated a Model M cannot reach its rated key-press lifetime. Its presence or lack of and its exact material can affect key feel.

Sources

ASK. Admiral Shark's Keyboards original content. License/note: CC BY-NC-SA 4.0.