Lauren Madison baby boy Striped Vestie Set With Satin Boxer Short 100% Polyester Made in US Dry Clean Only The Shorts have an elastic back for best fit button back closure 0-3 Months fits birth to 12 pounds, 6-9 Months fits 12 1/2 to 16 pounds, 9-12 Months fits 16 to 20 pounds,18 Months fits 20 1/2 to 23 1/2 pounds, 24 Months fits 24 to 27 pounds