(Pocket-lint) - Sony has expanded its line of truly wireless in-ear headphones to include a pair that are designed specifically for the rigours of all types of workouts and sports.

The Sony WF-SP900 'phones comprise of two earbuds and no wires at all. They are IPX5/8 rated so are dust and waterproof. You can wear them while swimming, even in salt water.

Similar to the WF-1000X equivalents released last year, the headphones connect to your Android or iOS smartphone via Bluetooth and have around three hours of battery life between charges. Luckily, they come with a charging case that will extend the battery lifespan by up to 12 hours.

The SP900s also have 4GB of their own storage on board and if you listen to music stored on them directly, battery life is extended to six hours for playback, up to 21 hours with the charging case utilised between sessions.

The best Lightning headphones 2021 for your iPhone or iPad

They come with NFC compatibility for easy pairing with many Android devices.

Three colour schemes are available - black, white and yellow - and each come with four sizes of swappable earpieces and three sizes of arc supporters to ensure a comfortable, tight fit.

Swimming earpieces are also included for those going underwater. You can also attach a leash cord for further piece of mind.

The Sony WF-SP900 headphones will be available from the beginning of November, priced at £250.

Writing by Rik Henderson.