Quick System Info is a great app, it’s main purpose is to give you detailed information on your SD card storage, A2SD storage, Internal storage, System storage, System cache, Memory and your Processor. Once you select a piece of information you get a breakdown of capacity, used and free for the selected memory.
You can also manage applications on your device with this app, it gives you detailed information on each application installed and it also allows you to clear data, clear cache and move to sd card.
This app also offers to kill applications for you as well, I feel the latest versions of Android do a good job of killing apps by itself and does not really need extra help, but if you have an app that has crashed you can kill it with this. The app also has notification indicators for RAM usage, CPU usage and WIFI usage. There are lot of changes that can be made in the preferences section so you can change the app to work the way you want it to. Overall it is a great app that helps to see detailed info about installed memory cards. Especially if you are having partitioning issues. There are two versions of this app, one is a pro version that contains extra features but is ad supported and the other has a few less features.