The Hedgehog system[7] involves a solid but flexible defence in which Black develops by b6, e6, Bb7, and Be7, before controlling the fifth rank with moves such as a6 and d6. The game typically involves extended maneuvering, but both players need to be on the lookout for favourable pawn advances and pawn breaks. The double fianchetto defence involves Black developing both bishops by fianchetto to g7 and b7.