Temporary Castration

The point of this is to exercise the will of the Master over the slave, such that the slave cannot cum without the approval of the Master. 
This control ranges from Chastity Control thought to  Temporary Neutering via Testicular Heating.
It is quite clear that a slave cock and balls belong to him Master (as does his sex drive), it is up to the Master to ensure that the slaves orgasm with his Master is the ultimate, anything else is Just Pants (crap).