Lay out the crotch-eight, as shown on the pictures below. Make it as tight as comfortable. The left and the right side should have the same length. Count the links of the chain to achieve this. The incomplete links A and B together count as one link. This means that on the right, there must be one complete link more than on the left. Once you have determined the number of links that fits you, use a marker pen to mark it on the chain, so that you easily find back the right size the next time.
The padlock should be big enough, so that you can easily lock the chain to your hands in it, and possibly a chain to your ankles if you want a hog tie. It should be in the orientation that is shown in the drawing. If you put it in the other direction, it will be harder to put the chain to your wrists in.
If you are a man, you are probably afraid for certain delicate body parts, but don't worry, nothing will happen to them. Your delicate parts are quite far forward, and your hands will pull the chain backwards. I still have mine after 20 years.
