Vionic Robyn Womens Comfort Flat in Buttercup. Size 7.5 Excellent used condition. Robyn is a perforated ballet flat that features Vionics VioMotion Technology to keep your feet supported and comfortable. VioMotion Support is an innovative approach to foot health. Vionic conceals biomechanical technology into each shoe. Allday comfort is a difference you can feel. Deep heel cup provides essential stability. Stylish and comfortable footwear that incorporates a podiatrist designed biomechanical footbed. I had foot surgery, and these shoes no longer fit.