Although this variation in {HEAD ~ size} is desirable, for convenience it has been found that a narrower range of {TAIL ~ sizes} from 10 to 1 microns or a narrower range from 5 to 1 microns with the maximum size 5 microns are adequate in most instances 
Although this variation in { HEAD ~ size } is desirable , for convenience it has been found that a narrower range of { TAIL ~ sizes } from 10 to 1 microns or a narrower range from 5 to 1 microns with the maximum size 5 microns are adequate in most instances
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH