a) solid cylindrical post insulator, which has an external glued metal attachment and is a type A insulator;

Note: Solid cylindrical post insulators are also referred to as "rod-shaped post insulators".

b) a cylindrical post insulator having a cavity with a joint or outer metal fitting, each of which has an integrally fired internal porcelain partition, which is a B-type insulator;

c) Type A cylindrical post insulators with inner or combined metal fittings;

d) a B-type cylindrical post insulator with an inner or combined plastic metal attachment;

e) Pin-type post insulators, which are type B insulators.