SICK WTB4SP-31311220ZZZ Photoelectric sensors. SICK WTB4SP-31311220ZZZ is a photoelectric sensors in the W4 family. SICK identifies this exact configuration as manufacturer article 1139073. The official technical record specifies Functional principle: Photoelectric proximity sensor; Functional principle detail: Background suppression, NarrowBeam; Sensing range min.: 4 mm; Sensing range max.: 130 mm; Adjustable switching threshold for background suppression: 10 mm ... 130 mm; Reference object: Object with 90% remission factor (complies with standard white according to DIN 5033). The linked SICK data sheet is specific to WTB4SP-31311220ZZZ.