100% organic cotton - GOTS Certified We’ve had feedback that this style runs a little small — we suggest sizing up for the best fit. Built for layering and warmth, our Sweatshirt Onesie is an easy go-to on cooler days. Designed with a roomy fit to allow plenty of space for wriggly bodies and busy little movers. Ribbed cuffs on the arms and legs to keep the cold out and reinforced PRYM snaps for easy changing. Ideal as an outer layer over bodysuits or onesies, it’s practical for everyday adventures when extra warmth is needed.