The Shakespeare Auto Winder II Bump Feed Trimmer Head is a durable pivoting line bump trimmer head with Auto Winding technology that eliminates the need for spools. The trimmer head is made from carefully crafted glass-filled nylon for superior durability and abrasion resistance, so that it can withstand the extreme demand of any job. with its Auto Winding technology, you never have to open the head, simply line up the arrows on the bump knob, insert the line, and crank. Giving you the continuous cutting benefit of a bump head without having to open the head or deal with tangling spools. That means cutting more with less downtime to get the job done faster, leaving you more time to do the things you want.