The following sequences activate this convention:
- showing 4 or more of the suit
- denying 4 of responders suit
- checkback Stayman, shows at least invitational values with 5 cards in the bid major OR 4 cards in the other major.
After 2♣, opener's rebids are:
If checkback Stayman is on after a 1NT rebid by opener, the following sequence is weak: