Benji Acol is a refinement on the Weak Two opening bid. It allows the opener a Strong Two bid.
For strong hands Benji gives two alternatives.
2C shows 8 clear winning tricks in an unspecified suit or a balanced hand of 18 to 19 points. The responder must bid a relay of 2D to allow a rebid. The opener rebids her strong suit or with a balanced hand bids 2NT. The responder bids the final contract.
2D shows 8 clear winning tricks in an unspecified suit or an unbalanced hand of 23+ points. It is a game forcing bid. The responder bids a relay of 2H to allow a rebid. A rebid at the 3 level shows the suit. The responder must now bid to game. If there is slam potential the responder can introduce a new suit or bid Blackwood. A rebid of 2NT shows 23 points and a balanced hand. The responder bids 3NT with 2 or more points otherwise passes.
2H or 2S shows a 6 card suit and fewer than 10 points. A weak 6 card minor hand is passed. Do not use Weak Twos if you have a 4 cards in the other major. The opener of a Weak Two has no rebid unless requested.
The responder can raise the opening suit to game or part game. If game is possible bid 2NT (ogust) to ask for more detail. The opener must rebid as follows.
3C - weak hand and weak suit
3D - weak hand and strong suit
3H - strong hand and weak suit
3S - strong hand and strong suit
If the opener has 25+ points and a balanced hand she rebids 3NT