The F.T.T. stands for the Fixing Team Tool. It is called the Fixing Team Tool because it is a combination of a mallet and a wrench, both found in the ISS toolbox. Since a mallet and a wrench sometimes work together it is called a Fixing Team Tool and because of this the repair(s) the astronaut has to make is quick. The mallet is very helpful because if the astronauts want they can make it (the mallet) a handle while using the wrench.