Not suitable or intended to be worn as sleepwear. Our own Wunsy Onesies are in a good quality fabric. You won’t be disappointed. Most buyers will buy up a size up especially if your child is taller than normal, or if you like a lot of growing room. Fastening: Zipper. Good zips that won’t break. Zips from the bottom and the top. Super soft fleece. Made from soft, comfortable and warm fleece that doesn’t dirty too easily. Machine wash and tumble dry and it will come out like new.