The Width
When taking measure of the width, you want to make sure you measure the widest part of the hoof. The width of the hoof determines the size of the hoof boot ("SG" 3-8).
The Length
When taking measure of the length, make sure you measure from the tip of the toe to the end of the heel bulbs. The length of the hoof determines whether you need a "SG" or a "SG-L".
The Heel Height
When taking measure of the heel height, make sure you measure from the ground to the deepest part of the pastern. The specific height will indicate which hoof boot type ("SG oder "SG-L") is needed.
CAUTION: Please make sure to thoroughly measure in a 90° angle. This image shows how it should not be done. A "wrong" angle can impact the measurements unfavorably.