Speedo Essentials – everything you need for a great swim. Speedo Essentials – everything you need for a great swim. Take on your training wearing the Endurance+ Thinstrap swimsuit from our much-loved Speedo Essentials range. Stylish in classic black, it features a wide open back and thin straps for unrestricted shoulder movement and comfort during training. 100% chlorine-resistant, our Endurance+ fabric is perfect for regular sessions in the pool.