This clock indicates only a second in notification area. This will go on when a screen is lit or you run this application. And this will go off 10 seconds later. Also this will go off when you tap the notify.
It's safe to download this application. Dr.T is the developer of the app which can be found in the Tools category. Second Clock was downloaded and installed by over 0,5K users and its most recent stable release was on Jan 22, 2016.
Google Play shows that this application is rated 2.8 by its users. Download the setup package of Second Clock 1.0 that is free of charge and read users' reviews on Droid Informer. The app is built for Android 2.3.3 and higher.