NX021/NX022,Standard/Quick Response Horizontal Sidewall Sprinklers (Ref. Figure A), are automatic sprinklers of the frangible bulb type, and standard spray, 1/2” orifice, 5 / 3 mm bulb. They are “standard / quick response-standard orifice sidewall sprinklers” intended for use in fire sprinkler systems designed in accordance with the standard installation rules recognized by the applicable Listing or Approval agency (e.g., UL Listing is based on NFPA 13 requirements).