Wristbands that change ever cruise. Untill, of course, they begin to recycle through the colors. Prevents B2B pax from buying Havana privileges on the first half only and sliding on in for the second half.
On our last B2B we were given dark brown for the first half and cream colored for the second half. Both were in an envelope on embarkation day waiting for us in our cabin.
And unlike chair hogs, staff actually enforce this.