These files were originally done exclusively for Photoshop, but with the huge number of requests for a Sketch version, it only made sense that we offer it for that too.
Sketch has come a long way since its first iteration. In fact, Sketch 3 now includes the assets from this file directly in the application. Many still prefer the standalone file, which you can still download here. Big thanks to the people at Bohemian Coding for integrating them and to Tyler Howarth for porting them.