Double low wing

A double low wing formation is a combination of star point stone with low extensions along the two adjacent sides (Black in diagram). Unlike other kinds of double-wing formations a double low wing formation is a bad thing to have (according at least to Guo Juan), since the opponent will not hesitate to invade at the 3-3 point. After this invasion the obtained thickness will be overconcentrated and not work efficiently with the low extensions.

Double-wing formation  

3-3 Invasion  

Invasion continued: black is overconcentrated