The "Weak 2's" are aggressive, defensive opening bids of  2 ♦ ,  2 ♥  and  2 ♠ . The opening 2-level bids are disruptive because they leave less bidding space for the opponents to communicate and to find a suit to bid.

These hands hold 9-11 HCPs and hold exactly 6-cards in the named suit. Since an 8+card fit is needed to control a suit, the partnership is close to finding a suit for a contract.

Note: An opening bid of  2♣  is not included. It is reserved to be a strong bid, indicating 22+ points, but not necessarily clubs.

There are 4 requirements for a Weak 2 opening bid:

Point Range:
9-11 HCPs
A minimal hand with 8 or less HCPs is very risky. Strongly consider a PASS with fewer than 9 HCPs.

Suit Length:
Must have exactly 6-cards in the opened suit. No more, no less.

Suit Strength (Critical):
The opened 6-card suit must have at least 5 honor card points (HCPs) (2 of the 3 top honors). Many players forget the honors in the named suit, and end up losing the contract.

Suit Selection:
The weak 2 openings are only  2 ♦ ,  2 ♥ , or  2 ♠ .

The opened suit cannot be clubs. An opening bid of  2♣  is reserved to be a strong bid indicating 22+ points, but not necessarily clubs.