Most people want their smartphones to be light weight and sexy, so they buy barely there cases that won’t cover up their phone’s slim lines. Those thin cases may look great, but they are doing nothing for your not so thin physique. Imagine if there was a way to use your phone in a normal fashion that could help you burn calories and tone muscles. There is. It’s the ToneFone, which is made of 100% British steel covered in soft, durable and grippy rubber. It’s basically a case for your iPhone 5/5s that turns the phone into a 1 kg or 1.5 kg dumb bell. For those of us who are metrically challenged, that translates 2.20 and 3.30 pounds. That doesn’t sound like a lot of weight, but if you are constantly picking up your phone to check text messages, facebook, emails, and calls, all those reps will add up to at least a little extra calorie burn by the end of the day. Currently available in white with gold and space grey ToneFones due in June 2014, these cases are priced at £22.90 for the 1 kg version and £25.40 for the 1.5 kg version ($38.02 – $42.17). Visit DesirableBody.co.uk for more info.