After a weak two bid and a takeout double, the opener's partner may bid
The lead directors are useful since the weak two bidder will
frequently be on lead after a takeout double in direct seat. Some people play a
variation of this gadget in which redouble is natural, new suits at the 2 level
are to play, and 2NT forces 3 to sign off at the 3 level somewhere. If you
choose to play that variation, you can redouble and bid a new suit to show a
forcing one suiter. Either of these variations is infinitely superior to
standard.
source: kfeiler@cpiusa.com (Kent Feiler)