From their release:
The bow wave tokens are designed to go on to the front of your naval ships so you can tell at a distance which direction ships are traveling. The eye candy doesn't hurt either.
The small tokens are design to fit the smaller 1/2400-1/1200 scale models. The medium tokens are designed to fit 1/200-1/600 ships. The large tokens are designed for 1/300 scale and larger.