haven't heard that before, and google wasn't helpful in deciphering its meaning :-)
Not that big? The face of the UK plug is 4.85 x 4.4 cm (1.9 x 1.7 in). A 3-prong plug in the US is 2.54 x 2.54 (1.0 x 1.0 in). Depth here can vary here as there's no fuse in the plug.