~Four Suit Transfers

This is the system preferred by some bridge professionals to transfer the 1NT opener into a 5-card major or a 6-card minor. If Four Suit Transfers are used, the stronger hand becomes declarer in all cases. Having the strong hand hidden will often create more difficulty for the defense and will often yield an extra trick for declarer. This is particularly true when the long suit is a 5-card major; when the long suit is a 6-card minor, there is less advantage to having the strong hand hidden. The 3C bid to transfer opener to 3D presents a problem in some systems; because of this limitation, many good players use 2S as a transfer into 3C. If appropriate, they then correct to 3D. Responder, with the weak hand will be declarer in 3D; however, the 3C bid can now be used for other purposes.

When playing Four Suit Transfers, the following bids apply after partner opens 1NT:

~2D: transfers to 2H. Responder may then pass with a weak hand of 0-7 HCP, invite game by bidding 2NT with five hearts or raising to 3H with six hearts and 8-9 HCP, or by bidding 3NT with 10-15 HCP and five hearts or to 4H holding 9-15 HCP and six hearts. These HCP ranges can be a bit weaker with certain card combinations.
~2H: transfers to 2S. The same shapes and point counts apply as in the above discussion.
~2S: transfers to 3C. Responder always has a weak hand of 0-7 HCP and 6+ clubs.
~3C: transfers to 3D. Responder always has a weak hand of 0-7 HCP and 6+ diamonds.
The shortcoming of Four Suit Transfers and the primary reason that many professionals prefer to use 2S to get to a final contract of 3C or 3D is that they prefer to use a direct response of 3C or 3D over 1NT to show a hand with about 5-8 HCP, 6+ cards in the long minor, and two of the top three honors in the minor with no other A or K in a side suit. The 3C or 3D bid asks partner to pass without a sure entry into the long minor suit or to bid 3NT with a sure entry. The hand for such a bid would look like this:
S T5 H 654 D KQT875 C 32 or S T5 H Q54 D 32 C AQ9854
If partner can ensure an entry to the long minor suit by holding Ax of diamonds in the
first hand (or maybe xxx) or by holding Kx in clubs in the second case, 3NT should be a sound contract. Otherwise, 3 of the long minor suit is the preferred contract.