"M12-1.25 Class 10.9 JIS-B1190 Serrated Flange Nut Zinc Plated"

Smaller Hex dimensions (across the flats) than DIN or ISO metric fasteners, these flange nuts fit in those tight spots where the hex of an ISO or DIN fastener is too large. These Class 10 nuts are serrated on the bottom of the washer face. JIS fasteners are O.E.M. equipment on Japanese import automotive & motorcycle industries. (MJISFN12F109)