Included are two tip up spools, designed specifically to improve Beaver Dam tip ups. These spools have a standard sized arbor, a handle, and a through hole to tie the arbor knot. These features greatly improve the function and versatility of the Beaver Dam tip up. These spools easily replace either the Beaver Dam spool with the side set screw or the previous model with the nut on the bottom of the spool. The arbor knot hole eliminates the need for tape and prevents the spooled line from slipping. You'll love the improvements!