This plug is used mainly in France and Belgium.

Grounded plugs fits both grounded and ungrounded socket outlets, but the old round ungrounded plugs do not fit grounded socket outlets.
Socket outlets of this type also accept the flat ungrounded Euro-plug and shaped ungrounded plugs.

Very often grounded French plugs, like the one on the picture, also fit German socket outlets.
(A german would of course say that these are German plugs that also feature French grounding)

The French grounded plug also fits Danish socket outlets, but the ground does not make contact.

Pins are on 19 mm centers, 19 mm long and 4.8 mm in diameter.
Maximum current 16A, but very often outlets are fused at 10A or less.
Standard: CEE 7/7 (French/German combination plug)