The mattress has 5" of firm natural latex foam made from certified organic latex! The zippered cover is made of organic wool fiber quilted to organic cotton fabric. All Savvy Rest quilting is free from cotton fiber. Cotton fiber attracts moisture and compresses. With moisture come dust mites, mold, mildew and fungus. Instead we use certified organic wool fiber. Wool wicks moisture so your baby sleeps cooler in the summer and warmer in the winter. The natural wool acts as a natural flame retardant. This mattress DOES meet all United States flame retardant guidelines and all of the CA flame retardancy guidelines naturally. Absolutely NO chemical flame retardants added. Fits all standard cribs 28" x 52". Approximately 5.5" thick.