Filled With 450g 7D Micro Fibers, Fluffy with Mideum Support 7D micro fiber has 7 holes on one fiber, offering good resilience of pillows,which can provide enough support for your neck and waist . Machine washable. Pillow Inserts' shell made from 100% brushed fabric, skin friendly, offering soft and comfortable touch. Fit 16inch x 16inch pillow cases or 15inch x 15inch pillow cases. Well vacuum package which ensure the hygiene. Once the package is opened, the pillow inserts will be fully expand within 48 hours. Also you can pat the pillow a few times to fasten this process.