A.) Accurate. Coil enclosed in cylindrical, molded, bakelite case with two 4-mm socket terminals for electrical connection. Valves of resistance of coil marked on cover plate and adjusted to an accuracy of .05%. Available in any value 0.1-1000amp. B.) Student’s as no. 1392A, but accuracy .1%. In a transparent, plastic case. Any value 0.1-1000amp.