At One Click Purchasing, we are your reliable source for the NSN part 4221B manufactured by Electrical Instrument Service Inc. We carry a wide range of popular NSN items on our website, including Resistance Standard like part number 4221B which is listed with the NSN 6625005853866 for easy identification. If you are interested in 4221B item, then take the advantage of our online RFQ service, or peruse our website as you see fit to find other items of interest that you may wish to learn more about.