It is a simple, inexpensive balancer that you supsend between your fingers. It is great for use at the field but obviously it isn't quite as accurate as other types of balancers.

http://www3.towerhobbies.com/cgi-bin...?&I=LXK247&P=7

I also have one of these but don't use it nearly as often: http://www3.towerhobbies.com/cgi-bin...&I=LXHY61&P=ML