Model RE-10 (W3800-1) increases the conductivity/TDS range 10 times when inserted into the sample-filled cell cup. Not available for Model 512T10 (W3760-4). The Porta-Pak Carrying Case (W3800-2) can be used with all DS and pDS Meters. Foam-lined and molded of sturdy ABS plastic. No solutions/buffers included. The Porta-Kit is a sturdy foam-lined case with 2 oz. bottles of pH 4, 7 and 10 buffers and conductivity standard solution. For use with W3740 meters only. Order W3800-3 for Models M6/pH, T2/pH and T6/pH (W3740-1thru -3); W3800-4 for Model EP11/pH (W3740-4).