Sensepoint XCD fixed gas detector, SPXCD: Sensepoint XCD product line., U: UL/CSA/INMETRO Certification., S: Stainless Steel enclosure material (316SS)., N: 3/4" NPT conduit entry (according to UL/CSA standards)., F: Flammable Catalytic Bead sensor type., X: User Adjustable gas range (e.g., 0-100% LEL).