Speedo Essentials – everything your child needs for a great swim.Speedo Essentials – everything your child needs for a great swim. Take on lessons and training wearing the funky Dive Thinstrap Muscleback from our much-loved Essentials range. Sporty with an eye-catching dual-colour panel design, it includes thin straps and a muscleback style for total flexibility during their swim. Quick-drying and stretchy to keep active kids comfortable, it’s made from Endurance10 fabric which is designed to keep its shape.