This European Standard specifies, together with EN 14399 1 and EN 14399 2, hardened and tempered plain washers intended for bolting assemblies with large series hexagon high-strength structural bolts and nuts with threads from M12 to M36 inclusive. Washers according to this standard can be applied under the nut only. Washers according to this standard are not intended to be used in direct contact with oversized or slotted holes. NOTE – Attention is drawn to the importance of ensuring that the washers are correctly used if satisfactory results are to be obtained. For recommendations concerning proper application, reference to EN 1090-2 is made.