I bought one of these to get rid of some of the sloppy steering.
The aluminium one that comes stock (at least in the RTR-models) gets worn quite fast. This is a fairly inexpensive way to solve that problem and get one that'll last much longer.
I've been using mine a lot, both on tarmac and in sand/gravel. Sand is probably the worst, but it's still not worn out. Of course it's not as tight as it used to be, but it has lasted much longer than the original!