The Starting corner hole is measured from the edge of the header to the CENTER of the hole, this will typically be 3/8”, 7/16” or 1/2”. The following holes are measured from the center of the hole to the center of the next hole. This can be easily accomplished assuming your holes are all the same size, by measuring from the left edge of the hole to the left edge of the next hole; this eliminates trying to find the exact center of either hole.

The last measurement will be from the center of the corner hole to the edge of the header.

If, buy chance, there aren’t enough spaces for as many bolt holes as you have, you can double up some of the like holes. For example, if you have five holes at 2” apart, list them as 10 in one of the boxes. If this is done, make a note that you have done so.

In order to double check your dimensions, measure from the center of the corner hole to the center of the opposite corner hole. These measurements are actually more important than the overall header dimensions.