A sliding hook flyer including one bobbin is now available as a retro kit for all existing Joy spinning wheels. Fill the bobbins evenly with the squeeze-and-slide stainless steel hooks. Graphite fiberglass arms make these flyers light and strong. New sliding hook flyer bobbins hold up to 30% more yarn. Due to the larger bobbins, the treadle may not fold completely with these bobbins stored in previous models of the Joy wheel.