Apple Watch Nike+

The Nike Sport band is the signature band which ships with Apple Watch Nike Series 2 and later. It is made from fluoroelastomer, however it has compression-moulded perforations for breathability. The perforations often have a contrasting colour in them.

Similar in fit and wear to the normal sport loop, the Nike sport loop bands contain a reflective thread which shimmers when light strikes it. Although both Nike bands are designed to complement the Nike Apple Watch, they can also be purchased separately.

Source https://en.wikipedia.org/wiki/Apple_Watch#Nike_Sport_Band_and_Sport_Loop