SL Dark Heart Theme is an Android personalization app developed by Ninth Avenue. It is a free theme for Smart Launcher that changes the wallpaper, clock and date style, bubble style and icon, drawer background and icons, and widget screen icons.

To use this theme, you need to have Smart Launcher installed on your Android device. If you haven't already installed it, you can download it from the Google Play Store. The theme is compatible with Android 2.0 and above.

To apply the theme, go to Smart Launcher's preferences, tap "Themes," and select the downloaded theme. The process is simple and straightforward.

If you have any suggestions, feedback, requests, or difficulties, you can contact the developer via the Play Store. They will assist you as soon as possible.

Overall, SL Dark Heart Theme is a visually appealing and easy-to-use theme that can enhance your Android device's look and feel.