Whorls allow the bobbin to turn at a particular speed in relation to the revolutions of the wheel’s drive band. This relationship is given as a spinning ratio. A slower (bigger) whorl will slow down the bobbin; a faster (smaller) whorl will speed up the bobbin. Each Schacht whorl has a bigger and a smaller ridge into which the drive band can sit, so each whorl gives two possible spinning ratios. See the ratios for each spinning wheel on its product page.
This is a slow whorl add-on for our Schacht spinning wheels.