The HoopKeyDoo is the perfect tool for machine embroidery on Berninas. Using the HoopKeyDoo, customers can easily tighten their embroidery hoops, even with thick material and stabilizer. Many buy two to accommodate their MegaHoops. Compatible with all Bernina hoops - excluding the Jumbo Hoop. Customers love these finger saving tools, especially those with hand ailments. Made in the USA.