Product introduction --- 4021-737 Pilot Assembly Use for Propane Gas only. Compatible with Part # 4021-737, Replacement Old Part Number 485-511A. The thermocouple is 24 inches, the thermopile is 36 inches, the pre-tube is 24 inches, and the ignition wire is 24 inches. Compatible with---Heat-N-Glo SRV485-511A, 4021-737, SRV4021-737, 485-511A, Quadrafire 4021-737, SRV4021-737, 485-511A, SRV485-511A. Heatilator 4021-737, SRV485-511A, 485-511A, SRV4021-737. Compatible with---AT-Grand-D, AT-Grand-B, AT-Grand-C, 7000XLS-, AT--C, -IN-B, Pier-38HV, FB-Grand, FB-IN, Bay-38HV, L-COR-, BE-32, BE-36, 6000XLSB, AT--B, R-COR-, -38HV, -, 6000CAMP, 6000TV-Oak, -42TVFL, 7000TV-, 8000TRC, 8000TRD, BE-41B, SL-950TR, SL-950TV, SL-350TRS, SL-550TRS, SL-550TV, SL-750TR, SL-750TV, 8000TVC. Compatible with--- -Fire Fireplace, QV36, QV32, QV36D, QV32-A, QV36DB-A, QV36-A, -Pier, -,QV36DB, QVI-30FB, QV36D-A. Fits Heatilator Fireplace Parts Models: NB4236, NB3933, ND3630M, NB4842, NB3630, ND4236M, ND4236 & ND4236L, ND4842 & ND4842L, ND3630 & ND3630L, ND3933 & ND3933L, ND4842M, ND3933M. Colour:As Shown Material:plastic+metal Matters needing attention---Before disassembling the old pilot assembly, to disconnect the electrical wires and gas lines connected to it, and then insert the pilot assembly. Remove the igniter, old gas pipeline, and old thermocouple wires, disconnect the old electrical wires, connect the wires, and install the gas pipeline. Due to different batches, there may be differences in product appearance and printed text, which not affect use Package Contents: 1 x 4021-737 Propane Gas Fireplace Assembly Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.