SICK GTB2S-N2451 Photoelectric sensors. SICK GTB2S-N2451 is a photoelectric sensors in the G2 family. SICK identifies this exact configuration as manufacturer article 1087766. The official technical record specifies Functional principle: Photoelectric proximity sensor; Functional principle detail: Background suppression; Dimensions (W x H x D): 7.7 mm x 27.5 mm x 13.5 mm; Housing design (light emission): Rectangular; Sensing range max.: 2 mm ... 120 mm 1); Sensing range: 25 mm ... 90 mm 2). The linked SICK data sheet is specific to GTB2S-N2451.