SICK WTB4FP-21311120ZZZ Photoelectric sensors. SICK WTB4FP-21311120ZZZ is a photoelectric sensors in the W4 family. SICK identifies this exact configuration as manufacturer article 1222999. The official technical record specifies Functional principle: Photoelectric proximity sensor; Functional principle detail: Background suppression; Sensing range min.: 4 mm; Sensing range max.: 220 mm; Adjustable switching threshold for background suppression: 15 mm ... 220 mm; Reference object: Object with 90% remission factor (complies with standard white according to DIN 5033). The linked SICK data sheet is specific to WTB4FP-21311120ZZZ.