Disclosed is a bed clothing system that has a bottom sheet and top sheet attached together at the corners of the foot end of the bed clothing system. The beam of emitted and reflected radiations travels along a path with known and constant discontinuities, in part through the air and in part through a cushion of low flow liquid, which flows with substantially laminar flow. That composition further comprises a modified release coating which substantially surrounds said core. When the process unit is loaded into the image forming device from a top open space, both ends of the rotational shaft are engaged with a pair of guides formed in side walls of the image forming device and guided down along the guides.