20pcs FSC PN4391 TO-92 SINGLE N-CHANNEL JFET SWITCH USA ship FSC PN4391 TO-92 SINGLE N-CHANNEL JFET SWITCH. Up for sale is one piece PN4391. MPN : PN4391. Selector Switch. Flux Cleaner. Tube Protector. Electronic Load. IC Regulator. byJuly 4, 2026