A multi-color emitting stick-type penlight, supporting pink, yellow, and green. - Color: Pink - Color: Yellow - Color: Green - Design: Stick type - Function: Multi-color emission Thank you for viewing. You can use it even without an app. I think you can do various settings with the app, but the app may not work depending on the phone. It might work on an iPhone, but I couldn't use it because my smartphone is Android. Please check the photos of the app screen. It seems that there are some iPhone models that can use it and some that can't.