This set rolls a 9mm Round bead and a 27 x 13mm tri-oval shaped bead. Beads can be pierced while they are inside this bead roller. About 20 bead piercing pins are provided. See our Pro Bead Rack in the Miscellaneous category! Polymer clay is the clay primarily used here at Poly-Tools, Inc., but other clay mediums can be used successfully with our bead rollers. Your satisfaction is guaranteed with all of our products!