Extra Square ratchet supplied with Turret Press

On four hole turret presses, a black square ratchet is tied to one of the posts on the press.  This is an extra index ratchet that fits inside of the black clamp that is mounted on the back of the ram of your press.   This piece causes the action rod to rotate which in turn rotates your turret.

The ratchet that was installed in your press should last around 10,000 loaded rounds.  When it does come time to exchange it, you simply place the new one on the action rod in the manner in which the old one comes off.  It's a very quick and simple process.