Because 1NT is such a useful opening, it pays to be able to interfere over it. On the other hand, because it is a strong opening, such interference often backfires. One strategy for overcoming this is to increase the chance of finding a fit after interfering. Thus, there have been a number of conventions developed to show two-suited hands as overcalls over 1NT. Following are a few: * Landy / Multi Landy * Astro / Aspro * Cappelletti * DONT * Brozel