What type of material composes these sheets?

Luxury Bamboo Bed Sheets: This line is made of a high bamboo to microfiber blend. This is our heaviest and most luxurious bed sheet set and a customer favorite.
Everyday Series Bed Sheets: These sheets are made of 100% Double Brushed Microfiber, a staple for any home. Very cost-effective and ultra-soft, these are our #1 bestseller by far with over 400,000 happy customers. They come in a very wide variety of colors that are sure to match anyone's taste and preference.