These are the threads used in the A Year in the Round BOM. Kit contains 24 balls of Valdani 12 wt. perle cotton. Each ball has 110 yards. Valdani 12 wt. cotton thread is the preferred thread for these projects, if you wish to achieve similar results. If you have never used Valdani before, you will be spoiled by this wonderful thread. You will never go back to anything else!