SICK GRTE18-F2437 Photoelectric sensors. SICK GRTE18-F2437 is a photoelectric sensors in the GR18 family. SICK identifies this exact configuration as manufacturer article 1094773. The official technical record specifies Functional principle: Photoelectric proximity sensor; Functional principle detail: Energetic; Dimensions (W x H x D): 18 mm x 18 mm x 73.5 mm; Housing design (light emission): Cylindrical; Thread diameter (housing): M18 x 1; Optical axis: Axial. The linked SICK data sheet is specific to GRTE18-F2437.