Abstract: An environmentally sealed key switch assembly has a key pad formed from a plurality of individual keys preferably arranged in rows and columns. A first elastomeric sheet has a plurality of holes corresponding to positions of keys in the key pad. Each hole stretches around a corresponding one of the keys in order to provide an environmental seal. A second and unbroken elastomeric sheet stretches under the keys to provide a second environmental seal. The keys press downwardly upon, stretch, and deform the second elastomer sheet and thereby operate an electrical contact. When the key is released the memory of the elastomeric sheets provide a return force to restore the key to normal.