Type H is used exclusively in Israel and Palestine. (Click here for the full list of all countries of the world with their respective plugs/sockets)
This earthed 16 amp plug is unique to Israel. It has three 4.5 mm round prongs, measuring 19 mm in length and forming a triangle. The centres of the line and neutral pins are spaced 19 mm apart. The centre-to-centre distance between the earth pin and the middle of the imaginary line connecting the two power pins is 9.5 mm.
Type H outlets also accept type C plugs. This was not the case before 1989, when the Israeli plug still had flat prongs. Power outlets made since 1989 accept both flat and round pin plugs. The original flat-bladed type H plugs have now become obsolete, but they can still occasionally be found. This plug is also used in the West Bank and all of the Gaza Strip.
Strictly speaking, type H sockets are incompatible with type E or type F plugs, because the diameter of the Israeli socket contacts is 0.3 mm smaller than the prongs of E/F plugs. However, if you push really hard, you can often force such plugs into an Israeli outlet. Bear in mind, though, that the appliance will not be earthed and that it is very hard to pull the plug back out!
Type H plugs are among the most dangerous ones in the world: the prongs are not insulated (i.e. the pin shanks do not have a black covering towards the plug body like type C, G, I, L or N plugs), which means that if a type H plug is pulled halfway out, its prongs are still connected to the socket! Little children run the risk of electrocuting themselves when pulling such a plug out and putting their fingers around it. Type H outlets are not recessed into the wall, so they do not provide any protection from touching the live pins either.