The castelli free ar 40 short sleeve jersey claimed to save 12 watts at 40kmh over a standard jersey the castelli free ar is a high performance piece of kit the free ar 40 blends the perfect fit and breathability for one of the best all round summer jerseys for 2015 with a number of colours to choose from and being part of the 2015 kit line up you can get complete the look castelli free ar 40 short sleeve jersey features saves approximately 12 watts at 40 kmh compared to a no