A membrane keypad is a key input device, typically externally mounted, which uses physical pressure to detect the closure of switches. It consists of one or more metal domes that connect two separated conductors. This construction results in a slim, light weight profile that provides built-in tactile and audio feedback. Key life is typically estimated at 1 million touches. Membrane keypads often include an adhesive backing that is used to affix them to a rigid surface. The simplicity of this low cost technology makes it attractive to industrial applications that require minimal input.