cylinder.
you can display many type routines. the set comes with 5/16" cork balls but can also work with the soft type ball like used with other type shells. if used with the soft type ball you lose the fair shell con display as the softball will come out of the shell whenever the shell is moved with the ball. when the shells are used with the softball they work like the standard type shells used today.
you are able to build your routine anyway you choose. the con game, a magical routine or a little of both.
there are many ways to bring some ending surprises with this set. here is an 