Hex Flange Serrated Bolts have a hexagon head with a built-in washer and under head teeth like serrations which bite into the surface to help prevent loosening. The built-in washer acts to distribute the clamping load over a greater area and the wide flange head is designed to provide the same holding power as a washer. Can be used to fasten objects together by inserting the bolt from the one end and securing it with either a nut on the other end or into a taped hole Material / Coating: Zinc Plated is the most common fastener of plating due to its the low cost and shinny bright silver finish. A thin layer of zinc is applied by either electroplating or mechanically. It is intended to be used internally. Whilst some people use it externally it isnt recommended if corrosion is a concern. If you want a fastener that will withstand the outdoor elements choose from our Stainless steel range Grade v Class Difference: Imperial fastenings are referred to as grades and metric fastenings are referred to as classes. Both have marking systems that make it possible to determine grade and class. An example is a ½” UNC bolt with 5 lines on the head is grade 8 and 3 lines is grade 5 both are regarded as high tensile. Metric bolts are slightly different if it has 4.6 then it is mild steel and 8.8 is high tensile. The markings on a stainless fastener indicate the grade of material and strength e.g. material G304 grade will have one of the following markings: A2-70 G304 A2 304 and G316 grade stainless will have one of the following: A4-70 G316 A4 316 Thread Pitch (Metric): Pitch means the distance between the peaks of two threads along a screw bolt or fastener expressed in millimetres (mm). Used when referring to Metric parts. For example a thread pitch of 1.50mm means that the distance between one thread and the next is 1.50mm Fastener length: is generally measured from the point where the surface of the material will be when the fastener is installed to the end of the fastener. All material is advisory only and its use by anyone is entirely voluntary. Reliance on it for any purpose by anyone is at the sole risk of that person and Bolt and Nut Australia is not responsible for any loss claim or damages arising therefrom.