This is a T-Cobbler breakout kit used for extending the GPIO interface on Raspberry Pi B+,2 or 3 to breadboard. It helps you to make the connections between Raspberry Pi B+/2/3 breadboard become simple.
This is a power module for the standard bread boards (Small and Medium sized). It's concave design so will not wast your proto zone. It also supports both 5v and 3.3v (both can be enabled on each power rail).
We think it is a must to have on your workbench, really.