On the left is the first Russian 7 tonne suspension П-7 (which is an abbriveation for 'Suspenstion-type, for 7 tonnes load'). On the right you can see a 4.5* tonne suspension (1920's).

* 4.5 tonnes was one of the standard loads for suspensions in Europe. Such insulators were used on 35-110 kV lines and in support strings on 220 kV lines.