The Idler Assembly, cataloged under National Stock Number 4320-01-221-1607, is classified within Federal Supply Class 4320 (Power and Hand Pumps) of the Pumps and Compressors group. The manufacturer of record is Circor Pumps North America Llc. The record lists 2 manufacturer part numbers for this item, enabling identification through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 2 items share a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Item Name | Idler Assembly |
| FSC / FSG | 4320 — Power and Hand Pumps (FSG 43) |
| Manufacturers | Circor Pumps North America Llc (CAGE 59180) |
| Parameter | Value |
|---|---|
| NSN | 4320-01-221-1607 |
| Primary Part Number | RSC218BG |
| Item Name | Idler Assembly |
| FSC / FSG | 4320 / 43 — Power and Hand Pumps |
| Manufacturer | Circor Pumps North America Llc |
| Status | ACTIVE |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Part Number | Manufacturer |
|---|---|
| RSC218BG PRIMARY | Circor Pumps North America Llc (USA) |
| SF-10523 ITEM 024 | Circor Pumps North America Llc (USA) |
| Reference | Meaning |
|---|---|
| RSC218BG | C/1 Advisory reference — outside the item-of-supply concept Siemens Energy, Inc. |
| SF-10523 | D/9 Drawing number reference only Circor Pumps North America Llc |
NSN 4320-01-221-1607 is a Idler Assembly, manufactured by Circor Pumps North America Llc, classified under FSC 4320, Power and Hand Pumps. Status: active.
NSN 4320-01-221-1607 has 2 manufacturer part numbers on file: RSC218BG (Circor Pumps North America Llc), SF-10523 ITEM 024 (Circor Pumps North America Llc).
2 possible matches (shared part number, not a government interchangeability claim): 4320-01-221-1608, 4320-01-221-1625. Verify interchangeability with system specifications before substitution.
No hazard code in the DLA record (HMIC N). Hazard information on this page is shown exactly as it appears in the DLA record.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-16.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.