Upper Knife, Babylock #61425
Guaranteed to fit Babylock Serger Models:
BL402 Protege, BL550, BL5370ED, SL4380ED, ST600L
Guaranteed to fit Riccar Serger Models:
RL739DE, RL749L
Guaranteed to fit Simplicity Serger Models:
SL4380BH, SL4380ED, SL4390ED, SL4690L