SICK GRL18-N2431V Photoelectric sensors. SICK GRL18-N2431V is a photoelectric sensors in the GR18 family. SICK identifies this exact configuration as manufacturer article 1085826. The official technical record specifies Functional principle: Photoelectric retro-reflective sensor; Functional principle detail: With minimum distance to reflector (dual lens system); Dimensions (W x H x D): 18 mm x 18 mm x 73.5 mm; Housing design (light emission): Cylindrical; Housing length: 73.5 mm; Thread length: 49.3 mm. The linked SICK data sheet is specific to GRL18-N2431V.