PVC Cushion Ergonomic Portable Inflatable Seat Cushion Pad Mat with Inflator Item Type: Inflatable Seat Cushion Material: PVC Optional Type: R200, R250, R300, R350, R400, R450 Inflated Size: R200 Outer Diameter: Approx. 18cm / 7.1in, Inner Diameter: Approx. 7cm / 2.8in, Thickness: Approx. 4.5cm / 1.8in R250 Outer Diameter: Approx. 23cm / 9.1in, Inner Diameter: Approx. 10cm / 3.9in, Thickness: Approx. 7cm / 2.8in R300 Outer Diameter: Approx. 27cm / 10.6in, Inner Diameter: Approx. 11cm / 4.3in, Thickness: Approx. 8cm / 3.1in R350 Outer Diameter: Approx. 32cm / 12.6in, Inner Diameter: Approx. 13cm / 5.1in, Thickness: Approx. 9cm / 3.5in R400 Outer Diameter: Approx. 36cm / 14.2in, Inner Diameter: Approx. 15cm / 5.9in, Thickness: Approx. 10cm / 3.9in R450 Outer Diameter: Approx. 40cm / 15.7in, Inner Diameter: Approx. 16cm / 6.3in, Thickness: Approx. 11cm / 4.3in Inflated Size Outer Diameter Inner Diameter Thickness R200 18cm / 7.1in 7cm / 2.8in 4.5cm / 1.8in R250 23cm / 9.1in 10cm / 3.9in 7cm / 2.8in R300 27cm / 10.6in 11cm / 4.3in 8cm / 3.1in R350 32cm / 12.6in 13cm / 5.1in 9cm / 3.5in R400 36cm / 14.2in 15cm / 5.9in 10cm / 3.9in R450 40cm / 15.7in 16cm / 6.3in 11cm / 4.3in R200 Diameter: Approx. 200mm / 7.9in Auricle, wrist, heel, ankle, etc R250 Diameter: Approx. 250mm / 9.8in Shoulders, arms, legs, etc R300 Diameter: Approx. 300mm / 11.8in Face, arm, leg, helper bone, etc R350 Diameter: Approx. 350mm / 13.8in Face, legs, elbows, etc R400 Diameter: Approx. 400mm / 15.7in (of thin people) back, hips, hip bones, etc R450 Diameter: Approx. 450mm / 17.7in (heavier people) back, hips, hip bones, etcSizeDiameterR200200mm / 7.9inR250250mm / 9.8inR300300mm / 11.8inR350350mm / 13.8inR400400mm / 15.7inR450450mm / 17.7in