A continuous heat set line for setting yarn, having spaced-apart, elongate, tubular entrance and exit cooling chambers interconnected by an elongate intermediate steam heat-setting chamber communicating therewith. The printing apparatus has at least one ink pen and a carriage for scanning the ink pen across a printing region. Further, the device may designate one or more external devices so that when a protection control unit of the device is activated, the device may only accept control instructions issued from the designated external device. An adjustment cam 28 can be connected to each hook module 20 and an adjustment drive 26 can be coupled to the adjustment cams 28 where the adjustment drive 26 moves the adjustment cams 28 to cause a skin stretching force at one or more hook modules 20 and to cause a skin reperfusion force at one or more hook modules 20.