RedPower Logic Parts can't be placed in the game world, but are instead used as components for crafting other logic items.
The Stone Wafer is used in the creation of most of the RedPower Logic recipes. It is the most basic component of all logic gates and cells. Some of its most notable usages are in the Timer, Wireless Receiver, and the AND Gate.
Not to be confused with stone wire, which is what the redstone receiver is crafted with.