Recently I got the BS cards in the mail that Ken sells. I am very happy with them. Another thing I would purchase is an index card. This would be a set of 6 clear cards the same size as the BS cards with index numbers printed on it. You could set it on top of the BS card and the correct index plays would align in the correct square. I would also buy SP21 cards. I don't know if you sell enough cards for it to be worthwhile, but it's a thought.