These capacitive proximity sensors allow sensing of metal and nonmetal objects through insulating materials such as wood or plastic and can be used to sense fill levels of liquids or powders. The 18- and 30-mm sensors have a simple potentiometer sensitivity adjustment. Operating voltages are 10 to 30 Vdc; shielded and unshielded versions and NO or NC units also are available. CK2 series 18-mm sensors carry IP65/IP67/IP69K ratings and provide an unshielded sensing distance of up to 15 mm, while 30-mm dc-powered CT2 series sensors have metal (IP65-rated) or plastic (up to IP69K-rated) housings with sensing distances up to 25 mm.