It occurs after partner bid for the responder and second defender in the following cases:

• for passed hand 1M was opened;

• after RHO double;

• if opponents have 18+ HCP.

Additional conditions:

• • support for the suit of the partner with at least one honor;

  • concentrated HCP in opener's and responder's suits;

  • responder's suit should have two of top three honors;

  • no HCP in other suits;

Examples: ♣ ♦ ♥ ♠

W   N   E   S   

1♠  X   3♦  - shows 3+♠ and 5+♦, 8+ HCP

W   N   E   S   

         1♣  1♥

1♠  3♦  - shows 3+♥ and 5+♦, 9+ HCP

W   N   E   S   

             P

1♣  1♦  P   2♥ - shows 3+♦ and 5+♥, 10+ HCP

W   N   E   S   

             P

P   1♠  2♦  3♥ - shows 3+♠ and 5+♥, 8-11 HCP