FLANGE NUTS – PLAIN & SERRATED The necessity of using a washer is eliminated as the bearing surface of the face of the nut is larger thereby effecting a stronger grip. Serrated Nuts are used to reduce the loosening effect as whilst tightening these nuts force a grip on the mating component. PRODUCT RANGE : Specification : DIN 6923 / CUSTOMER STANDARDS Thread form : Metric British / Unified sizes Size Range : M6 to M16 Finishes Available : Bright Zinc, Zinc Blue, Zinc Yellow, Zinc Black. Hexavalent or Trivalent chrome.