Add the same meter movement protection that has been in place since the 260 series 5 to your 260 series 1-4. See the complete on-line instructions for installation
The original version of the kit is still available (while supplies last). The original version included two solder lugs and a single varistor (back-to-back diode package). The current version also includes the solder lugs but instead of a single Varistor Package, the two diodes are individual, like the current production 260s and 270.