The CX Sport are Sennheiser's latest wireless headphones, which join the CX 6.00BT and HD1 Free (which I just compared earlier this week), but designed for more athletic activities.
You can say this because, despite appearing almost identical to the CX 6.00BT (which is, in turn, extremely similar to the HD1 Free), the CX Sport has the word "Sport" in the name, and also comes in A bright yellow color scheme with some additional rubber fins. The CX 6.00BT, as a reference, has a blue color scheme and no fins, but otherwise it seems to be the same hardware, up to six hours battery life and Bluetooth AptX support.
The main difference, apart from the color – is that it is said that the CX Sport is "resistant to splash and sweat", which Sennheiser does not claim about the other models.
The CX Sport will be available through Sennheiser in June for $ 129.99, slightly more than its counterpart of $ 99.99 CB 6.00BT, and slightly less than the HD1 Free accelerator for $ 199.99.