This is how the factory riders start!
The factory start is mounted directly on the fork. Before the start, the fork is dipped and fixed in the desired position to shift the center of gravity forwards. This to a large extent prevents the front wheel from lifting at the start, thus providing greater traction and perhaps securing you the odd holeshot or two. The first time the fork dips, the fixing is slackened and the fork released automatically.
Helps keep center of gravity forward.
Keeps front wheel down during starts for better traction.
Releases automatically when fork is compressed the first time.