Peace of mind in the Pool - ensures little accidents are contained within the nappy SPF 50 - Sun Protection, Maximum UV Protection Stylish Swim Wear for Infants and Toddlers Clean, Warm and Happy in the Pool Allows longer to be spent in the pool than traditional swimwear Reusable and Easy to Clean Supple 1mm Neoprene (wetsuit material) with soft fabric ribbing The most essential item in your infants swim kit Most pools make a swim nappy like this mandatory due to very strict hygiene rules. Recommended by leading swim schools All you need for peace of mind in the pool and at the beach. You may also use it with a liner or simple swim nappy for ease of cleaning but it will also be fine on its own. Splash About are the childrens swim wear specialists and you can be assured of the highest quality product which can be used again and again. To reuse your Happy Nappy immediately after cleaning, roll the nappy in a towel and squeeze. It is now ready to use without discomfort. The Happy Nappy is the only nappy insisted upon by many swim schools. The sizing guide works for most babies but like us they come in all shapes and sizes They should give room for growth while also being a good snug fit to keep baby warm- just like a wetsuit. If you're not sure between two sizes,we would advise to size up as these have been small fitting. You can see full size guide linked here for guidance.https://www.splashabout.com/size-guide/ The Happy Nappy is the answer to what has previously been a serious risk with baby swimming: Because any passing of solids (or semi-solids) into the water can create the serious risk of an infection called cryptosporidium being passed into the water. So that if an accident occurs in the swimming pool, it can mean the pool has to be closed and all classes cancelled for that day.