These Flip Transitions were created when someone asked me how to do a 3D flip in FCPX.
Sadly the default flip transition forces a solid background. So these ofter you 3 different types.
1. On edit going from one item to another
2. Start at edit, to bring items in from nothing
3. End on edit, to have items leave
Just pick from the pop up menu on which type of transition works best for you!
Here is a little video to see what the transitions look like.