SICK GRSE18S-P2421V Photoelectric sensors. SICK GRSE18S-P2421V is a photoelectric sensors in the GR18 family. SICK identifies this exact configuration as manufacturer article 1085765. The official technical record specifies Functional principle: Through-beam photoelectric sensor; Dimensions (W x H x D): 18 mm x 18 mm x 55.9 mm; Housing design (light emission): Cylindrical; Housing length: 55.9 mm; Thread length: 31.7 mm; Thread diameter (housing): M18 x 1. The linked SICK data sheet is specific to GRSE18S-P2421V.