BridgeHands

SOS Redouble -  After an opponent makes a penalty double, partner's redouble in either the direct or passout seat demands partner find a more suitable contract to avoid a costly penalty.

Direct Seat Example:

1N - (X) - XX              Agreement usually forces 2C.

(1S) - 2C - (X) - XX;   Advancer short in partner's suit, asking for a red suit rebid

Passout Seat Examples:

2D - (X) - P - (P);
 XX                           Opener needs help, responder asked to bid another suit

Also see Moscow Escape, Exodus, Bergen Redouble Over Notrump