Industry standard 18 mm diameter threaded body has flat sides allowing it to be mounted like a tubular sensor or against any flat surface Right Angle viewing models mount in a depth of only 6/10th of an inch Perfect Prox technology provides exceptional background rejection and application problem-solving Visible sensing beams let you see where the beam is aimed for quick setup and alignment Solid polyurethane housing completely encapsulates internal circuits for high resistance to shock and vibration Adaptable modulation circuit provides immunity to crosstalk from other closely mounted sensors The industry's only background rejection sensors with a two-wire circuit design Models available with both AC and DC operation in a single unit - up to 264 VAC Four-wire DC sensors offer both NPN and PNP outputs Output status indicator visible from a wide 270 degree angle