<ul><li>1/4&quot; Series (Aro Series) Type &quot;B&quot;</li><li>Hardened steel balls and stainless steel springs.</li><li>Heat treated to reduce wear on critical mating surfaces.</li><li>The Aro Series of plugs are easily identified by the distinct appearance of the plug.</li><li>The couplers are identified with one wide groove on the sleeve.</li><li>Couplers interchange with Aro 210 series as well as units produced by other manufacturers.</li></ul>