Cool & Comfy Silk Flat Sheet (Eucalyptus)Cooler for the summer, warmer for the winter. Our Flat Sheet (or Top Sheet) even doubles up as a cape for aspiring super heroes. Our fabric is made from eucalyptus that's grown using 95% less water than cotton, no farmable land, and zero herbicides or pesticides. It's naturally hypoallergenic, resistant to bacteria growth and has the same sleep benefits as conventional silk. As with all our sleep products, we only use what the planet would want us to.