Gerber Baby Boys' Work Site Thermal 2 Piece Underwear Set 80% Cotton/20% Polyester Machine Wash 80% Cotton/20% Polyester for comfy fit PJ's are designed to fit snug for child's safety. Gentle elastic covered waistband on pant provides a great fit and easy to pull up and down for changing diaper or learning to potty train. Easy to care for machine wash and dry.