Celestron's Counterweight Bar Assembly is a metal rod which runs the length of the telescope tube, attaching to both the front and rear cells.
Counterweights can be attached and moved along the length of the assembly, as well as perpendicular to the assembly, for better dynamic balancing.
A 2.5 lb (1.1 kg) counterweight is included, and the optional #94193 extra counterweight can be added for those demanding the ultimate in balance.