The 64 oz setup is the largest bobbin size in the industry. It can fit over 4 pounds of worsted weight single. It was originally designed for the Firefly, as a production unit for spinning and plying bulk quantities of yarn. It also fits the MACH III - although most spinners prefer using the electric Firefly base to power the momentum, rather than treadling this workhorse manually.
This setup is great for the fiber artist who wants all the yardage they could ever dream of. It is perfect for making huge art yarn and bulky skeins, but engineered to spin fine yarns as well.
Upgrades include everything you need to add a new size to your wheel base:
A head (attaches into the base of your wheel) A flyer (has a back with whorls, arms, and an orifice bar and holds the bobbin) A hook orifice bar (attaches to the flyer magnetically) A bobbin (slides onto the flyer and is secured to the back with a magnet) The 64 oz setup fits the following wheel models: MACH III, Firefly.