Cotton PREMIUM COTTON PERCALE FITTED SHEET: Provides the optimal mix of comfort, durability and easy care. No added chemicals, flame retardants or formaldehyde. MIX & MATCH: Designed with toddlers in mind, let them mix & match fun prints and inspiring colors to personalize their dream space. Sheets, pillowcases, and pillows sold separately. EXTRA DURABLE & LONG-LASTING: 200 thread count makes these sheets extra durable to last through the toddler stage. Use with a BreathableBaby Mattress Cover (sold separately) during potty training! EASY CARE & SOFTER WITH EVERY WASH: Machine wash, tumble dry low. Wrinkle and shrink-resistant 100% cotton gets softer with every wash. And the 2-pack means there's always a backup. FITS 52" x 28" CRIB & TODDLER BED MATTRESSES: Continuous extra wide elastic and 9" (23 cm) deep pockets help ensure a secure fit for crib & toddler bed mattresses measuring 52" x 28" (132 x 71 cm).