The most essential item in your baby swim kit is your Happy Nappy. In fact, most baby swim schools in the UK now recommend that all of their babies wear one. Afterall, the idea is that you go swimming with your baby and not with the contents of his or her leaking nappy! They are made of 1mm supple, stretchy neoprene and finished with super soft, snug fitting, deep bands of fabric with a high rubber content to keep all nasties inside. Designed by us with swim teachers, parents and babies in mind! So simple and yet so effective, no ties, no Velcro, no elastic. IT WORKS!! Can be worn with or without a conventional swim nappy - a liner is advised for ease of cleaning. Tested and improved upon with the leading UK swim teachers. Sizes: XS Premature: 3-4kg, Waist 32cm Leg 16cm S 0-4 Mths: 3-6kg, Waist 34cm Leg 18cm M 3-8 mths: 6-11kg, waist 36cm Leg 21cm L 6-12 mths:10-15kg, waist 38cm, Leg 24cm XL 12-24 mths: 13-18kg, waist 40cm, Leg 26cm XXL Toddler 24+ months: 16kg+, waist 42cm, Leg 28cm