I acquired my Mad Rock Max Air from Mad Rock in 2009.
The Mad Rock Max Air is forged from aluminum alloy and then soft anodized. Mine is 56 mm. long, 47 mm. wide, 100 mm. high, and weighs 55 g. The slots are 35 mm. long and 16 mm. wide. The top of the Omega oval carabiner that I use for comparing belay tubes sits 7 mm. below the ends of the slots. The Max Air has a flexible, plastic-covered, cable keeper.
One side of my Max Air is marked with the "MAD ROCK" and "HE1," while the other has two rigging icons, one showing the high friction arrangement with a "+" in a circle underneath, and one one showing the low friction arrangement with a "-" in a circle underneath.
The Max Air has several distinctive features, but overall, performs like most devices of this type. The rope slots are hour-glass shaped, but this does not appear to affect their performance. The Max Air is slightly asymmetrical, giving two distinct riggings. These are screened on the side of the device. One would expect a difference in friction for the two riggings, with more friction if the braking line runs over the shorter end; however, I do not notice much difference. The plastic-coated cable keeper is moderately flexible, but stiff enough that it tends to stay out from under the rope.
The is essentially the same as the Climb Axe Max, Kong Chuy, Ocùn Tuber, and Simond Tubik.