Aluminium Countersunk Bolts and Washers. High Tensile Anodised Aluminium Countersunk Bolts are measured in length including the head, bolts here are available individually or in any quantity. We can supply countersunk washers separately which are designed to be used with this type of bolt. Ideal where a large diameter spread is required to prevent bolts pulling through bodywork etc and where a low head profile is essential. By using a separate Bolt and Washer we can obtain a larger outside diameter than would otherwise be possible.