In summary, the SCHURTER PSE metallic piezo switches are a series of sealed switches based on piezo crystal technology. There are no moving parts to wear out, thereby the switches provide a long product lifetime with greater than twenty million cycles. With fully sealed anodized aluminum or stainless steel housings, protected to IP69K, and a mechanism that will not freeze, the PSE series has an operating temperature range of -40°C to 85°C. PSE switches are available in point illumination, ring illumination, and non-illuminated versions, with a very flat front surface, which helps make them vandal-proof, plus the face can be laser etched with either standard legends or customer supplied lettering.