A thermal control circuit for an integrated power transistor includes a current generator controlled by a turn on signal, a sensing resistance in series with the power transistor, and a current limiter acting when the voltage drop on the sensing resistance overcomes a certain value. In a preferred embodiment, the present invention allows a user to obtain rights to access media files of selected content, which may include a song, album, movie, etc. The hub is interengaged with a housing having a main body portion with the needle cannula extending through a forward opening therein, and a rearward extension with a longitudinal slot extending axially therealong between a forward slot end and a rearward slot end, such that the lever of the hub extends through the longitudinal slot and is locked at the forward slot end thereof. The tooth flank surface of the tooth that a vertical chain link contacts under the effect of a load is dimensioned and profiled in a special manner. The measurement can be taken when the calibration wafer carrier is positioned substantially at a polishing height, which is substantially equivalent to a height of a normal wafer carrier during a chemical mechanical polishing operation.