You will need Bowl Reversing Jaws for the reverse mounting of a turned bowl or small platter. The jaws have rubber plugs that move to suit the size of your work. Remove spigots or apply a finishing cut to the outside of a work piece. The rubber pegs can hold the work internally or externally, whichever is best for the shape of your work. Take care if the wall is thin as these jaws apply some pressure and cause damage (as I found out myself).
