Will older 42mm Apple Watch cases/straps fit the 42mm Series 2?

Hi

All Apple Watch bands sold to date by Apple will fit any Apple Watch of the same case size (38mm or 42mm).

Note that the manufacturer of the case that you refer to states that the case is compatible only with Apple Watch 42mm (2015). You may wish to ask them to clarify whether it will also fit the Series 2 model, which has slightly different dimensions the first generation watch.

For the best performance and results, use only Apple branded or Apple authorised bands. Apple advises that third-party bands:

• May not fit properly;
• May contain materials that cause skin sensitivities or other health concerns;

  Every material in Apple bands that touches the skin has been extensively evaluated in accordance with Apple's specifications.

• May interfere with the Wrist Detection feature;
• May damage Apple Watch:
  • Unauthorised third-party bands may have components that do not meet Apple's design specifications.
  • Such bands may, for example, become jammed in the watch (an example of this has been posted here previously), release too easily, fail to resist slide-out force, corrode easily or exhibit other issues.

More information:

https://help.apple.com/watch/#/apd9714c20d9

http://www.apple.com/shop/watch/bands

You're welcome!