In Contract Bridge, a jump to 4 Diamonds to show Hearts, or 4 Hearts to show Spades, after a 1NT or 2NT opening.

Opener is required to bid four of the suit that is shown. It is used to show a hand weak in high cards, but with extreme distribution, and usually no slam interest. Texas Transfers combine the advantage of making the no-trump opener the declarer with the advantage of preempting the opponents.

For example:

South deals
North-South vulnerable

                S: 7 5
                H: A Q 9 8 7 5
                D: 7 6
                C: 8 5 2

   West                             East
S: K 9                           S: Q J 10 8 6 4 2
H: J 10 6                        H: 4
D: A 9 5 4                       D: 8 2
C: A 9 7 4                       C: Q J 10

                S: A 3
                H: K 3 2
                D: K Q J 10 3
                C: K 6 3

Without transfers, the bidding might go:

     West          North         East          South
                                             1 No-Trump
     pass        4 Hearts        pass          pass

Since North is the first player to bid Hearts, North becomes declarer, and East has to make the opening lead. The contract is easily set if East leads a Spade or a Club. South can easily take ten tricks on any other lead by establishing Diamonds.

Using Jacoby Transfers, the auction could be:

     West          North         East          South
                                             1 No-Trump
     pass        2 Diamonds    2 Spades      3 Hearts
     pass        4 Hearts        pass          pass

Now South is the first player on his side to bid Hearts, and becomes declarer. West makes the opening lead, and the contract of 4 Hearts can only be defeated if West leads the King of Spades. This lead, however, is easily found, because East was given the opportunity to make the relatively safe bid of 2 Spades. (In fact, East can take ten tricks if Spades are trump.)

Using Texas Transfers, the auction would be simpler:

     West          North         East          South
                                             1 No-Trump
     pass        4 Diamonds      pass        4 Hearts
     pass          pass          pass

East has been robbed of the opportunity of making a safe 2 Spade bid. Now West, on lead, might still guess to lead the King of Spades, but without the information given to him by his partner's Spade bid. Since King-doubleton is usually a horrible lead, West will most likely lead a trump, allowing the contract to make.