This is a HOMCA donut cushion. Material: Memory foam Color: Blue Size: 45 x 38 x 7.1 cm Weight: 0.93kg I tried it a few times at home and then stored it. As you can see in the 5th and 6th images, the inside is also very clean. ≪Product Description≫ ＜Ergonomic Design＞ ・The HOMCA ergonomic seat cushion is available in three different contour designs. 　The hollowed-out edges prevent direct pressure on the tailbone. The hollow design lifts the body and maintains a healthy sitting posture. 　It maintains an ideal sitting posture for a long time without causing discomfort to the back or lower body. ＜High-Quality Memory Foam＞ ・The seat cushion uses high-density, resilient, high-quality memory foam to firmly support the lower back. 　It is resistant to sinking even after prolonged use and maintains its softness. 　The posture correction cushion is heat-resistant and adapts to the curves of the body by sensing body temperature. 　It provides the comfort needed for sitting work in the office. ＜Multi-Situation Support＞ ・Working on a hard chair can be difficult if you have a tailbone or hemorrhoids. 　This cushion can be used not only on hard chairs at home and in the office, but also in cyber sports chairs, in cars, and by postpartum pregnant women. 　Wherever you sit, this cushion will make your back, lower back, and thighs incredibly comfortable. ＜High-Quality Materials＞ ・The bottom has a non-slip feature. The round seat cushion has a breathable mesh cover for a comfortable and cool sitting experience. 　The cover is removable and machine washable. Please understand that this item has been stored at home and has been inspected by an amateur. Thank you for looking.