Its small panel similar to the Android Volume control panel.
It's very useful in case of:
Volume keys stops working.
Case/Flip Cover that hinders pressing Volume keys
And for friends like me, I always want to avoid pressing physical phone button to
saving volume keys from tearing off ;)

Volume Button is exactly the same as Android Volume Panel.
1. Adjust Ringer, System Volume, Media, Notification & In Call Volume
2. With the White Background and dark controls, visibility in sunlight are high.
3. Access any time without closing app. as its have optional Permanent Notification option.
4. Fast access as its directly accessed from notification: Volume in notification.
4. Consumes NO battery at all

So light simple and easy to control different volumes.
Its fast & smooth.

Intelligent Caller ID functionality added. Caller ID now helps you identify callers - even the ones not in your contact list. This feature is optional and you can adjust or disable Caller ID at any time in the settings menu.