Communication: The thermal decomposition of polystyrene clusters prepared by using 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl as a branching agent was studied. The weight-average molar mass ((M) over bar (w)) and the radius of gyration (R-g) of the resultant clusters can be scaled as (M) over bar (w) proportional to R-g (3.0 +/- 0.1), revealing that these clusters have a uniform chain density. Moreover, the dynamic properties of such clusters converge Unexpectedly faster than the static properties as the molar mass decreases.