Do Bands for Apple Watch 1 fit Apple Watch series 2?
Yes, straps that were made for the Apple Watch 1 will fit the Series 2. Apple kept the same exact connector on the bands for Apple Watch Series 2. The case of the Apple Watch 2 is also the same size as the Apple Watch 1. This means that any strap that was made for the original Apple Watch will fit your Series 2!
This question was also answered in Apple's communities as well.