I know the 3 bolt ones were on sale at zxtuner for $40 a while back. Might still be. The only bad thing I heard about them was that 3 bolt cam gears could loosen more as oppossed to 5 bolt designs. And this was directed towards 3 bolt cam gears, not MAC specifically. Again, only what I heard, don't one any adjustable cam gears. Agree with Lip, can't beat the price.