POST OFFICE BOXES Brass Plugs

A) 3 Ratio Arms
B) 4 Ratio Arms
* The 3-Ratio P.O. Box has sixteen wound coils 1, 2, 2, 5, 10, 20, 20, 50, 100, 200, 200, 500, 1000, 2000, 5000 ohms and two proportional arms each with coils of 10, 100, 1000 ohms .
* The 4-Ratio P.O. Box has sixteen coils as above and two proportional arms each with coils of 1, 10, 100 and 1000 ohms. Also incorporates infinity gap,
* double Brass terminals,
* Two spring keys for battery and
* galvanometers can be provided at extra
* incorporated in teak polished wooden box.