For decorative appliqué work and embroidery. "Ensures consistent even fabric tension for smooth, precise, pucker-free stitches. Perfect to stitch in narrow spaces and useful to stitch where it is difficult to set an embroidery hoop such as tailored pouches, shirt collars or sleeves of shirts." 3 3/8" diameter Dome is stainless steel and band is silicone rubber There is also a YouTube video: search "Clover Stitch Dome"