100% Cotton! These are 100% cotton and nice and thick like the old-fashioned brands - not like the supermarket kind. Stretchy for easy dressing. You'll love them. Lap style shoulder envelope neck for ease of dressing. True to size. Double stitched for extra durability. Sleeve edges are finished with interlock binding. Made of 100% ringspun interlock cotton for extra softness. Made in England. Age/Size Weight Height 0-3 Months 10 lbs. 19-22 inches 3-6 Months 14 lbs. 22-25 inches 6-12 Months 18 lbs. 25-28 inches 12-18 Months 23 lbs. 28-31 inches 18-24 Months 27 lbs. 31-34 inches 24-36 Months 31 lbs. 34-36 inches