https://www.rcfastener.com/bolts/serrated-flange
Serrated Flange Bolts & Screws | Hex Head Serrated Flange Screws
Designed for use in applications where loosening forces are present like vibration, these flange bolts provide more strength than a standard machine screw....
serrated flange boltsscrewshexhead
https://www.fastenersuperstore.com/products/404101/hex-flange-frame-bolts
M6-1.0 x 40 mm Hex Flange Bolts / Non-Serrated / Grade 8.8 / Plain / DIN6921
M6-1.0 x 40 mm Hex Flange Bolts / Non-Serrated / Grade 8.8 / Plain / DIN6921
https://dg--chover.en.made-in-china.com/product/BGAYkbeCaxUg/China-DIN-6921-Grade-4-88-8-Galvanized-Serrated-Flange-Bolts-with-Colored-Flange-Screws.html
DIN 6921 Grade 4.88.8 Galvanized Serrated Flange Bolts with Colored Flange Screws - Auto Parts and...
DIN 6921 Grade 4.88.8 Galvanized Serrated Flange Bolts with Colored Flange Screws, Find Details and Price about Auto Parts Hardware from DIN 6921 Grade 4.88.8...