This natural innerspring crib mattress employs traditional Bonnell style coils surrounded with quilted layers of pure wool that, with extra tufting, achieve a truly firm mattress to provide that perfect feel for a newborn baby. Organic cotton fabric on the outside, pure wool batting on the inside. 252 coils, 15 gauge. Click HERE to read more about the best cotton and wool used in this mattress and to view the organic certifications. The natural wool acts as a natural flame retardant. Absolutely NO chemical flame retardants added! Fits all standard cribs 28" x 52". Approximately 5" thick.