I went to their site because I was interested in DOUBLE points. I re-read it a few times and believe that the following is "the rules".

When you apply you must make a "transfer balance" to "join" the 2x points "club".

If you are a "member" of the 2x club, in the month that you "cary a balance" (i.e. pay interest) then the purchases made that month get 2x points. As noted above, if you carry a balance then no grace period.

However, with correct timing, (purchase late in billing cycle and pay all be a small amount inmediate after billing cycle, it may work very well. With the lower Intro % it could work out to a good deal. I am investigating into this some more.

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