Normally my preference is to swim without a cap, but a swimming pool I frequented required all swimmers to wear caps, so I had to buy one. First I got a latex one ... big mistake! Next I bought this silicone cap and found it to be consistent with the quality one expects from Speedo. There is a knack to putting it on (which involves a bit of stretching and starting from the forehead) but it becomes second nature. It kept my long hair contained and, as a useful bonus, protected it from a lot of chlorine damage, although inevitably the edges got wet (for those who do not know, swimming caps are designed to make you swim faster, not to keep your hair dry). I also like how it stops a lot of water from getting inside my ears.
This cap is tough and durable, and it still looks and feels like new after a year of thrice-weekly use. Mine has a really cool design in red, white and blue that makes it quite unique so that its ownership is never in doubt!