To change the size of your Rubber Dive Strap yourself, you are going to need your spring pin tool and a pair of scissors.
The first thing you are going to do is take a look at the strap. Notice that it is sectioned off. This process would be similar to taking links out of a stainless bracelet watch but instead of unscrewing links, we are actually going to cut sections out of the strap.
Go one side at a time. Using the spring pin tool, you are going to push down on the spring pin in the clasp. That pops off one side and you will notice there are several sections on your strap. Do one section at a time because you do not want to cut the strap too short.
Line up your scissors two millimeters on one side of the filler bar and cut off that section. Next, take your spring pin and push out the filler bar, put the spring pin in, and attach the clasp.
You will notice there are three settings on the side of the clasp. This allows you to tighten the strap or loosen it as needed. If it is not enough, you can cut the strap down a little further on each side.