A flowmeter for metering the volume of flow of a fluid through a filter, to enable the level of filter usage to be indicated. The cooling system includes at least one generator having a plurality of external fins disposed around at least a portion of the periphery of the generator. Further provided by the invention are PFMSET polypeptides, and functional fragments thereof that contain a PR, SET, PRAZ or PKZL domain of a PFMSET polypeptide. Thus, reliability of defect detection in the mask may be remarkably improved. The invention is particularly directed to reduction of the adsorption of proteins on surfaces of contact lenses and other medical prosthetics. The third reactive ion etch includes an etching chemistry that performs at a lower etching rate on the hard mask layer than on the layered sensing stack.