Part number 500-2521 appears under 4 stock numbers

Manufacturers reuse part numbers across items. Each stock number below is its own federal item record — pick the one your drawing or solicitation cites.

8415-01-258-2939 — RETAINER,KNOB · FSC 8415
5950-00-372-0562 — COIL,RADIO FREQUENCY · FSC 5950
5310-01-269-9247 — WASHER,SPRING TENSION · FSC 5310
1650-01-603-9899 — NRP,COVER,TENSION,S · FSC 1650