How to tell which Rollei Bayonet filter mount

There is much confusion when trying to fathom which vintage filter to buy for a Twin Lens Reflex camera that has a bayonet mount such as a Rolleiflex or Yashicamat. The reason is there are three sizes. Rollei Bayonet I Rollei Bayonet II and Rollei Bayonet III. The Bayonet I is sometimes described without the …