The strap comes in two pieces and it looks like to can adjust both sides but the piece that has the clasp looks like it's adjustable, but it's not. You cannot remove the pin. What I had to do is cut down the other piece as small as it would go, then attach it to the other end of the clasp with a spring bar.
Behind the clasp is an adjustment mechanism that allows you to adjust the strap by 15ml. I have small to average sized wrists, with the strap on the smallest size it fits perfectly.