How to allow for that adjustment, though, was a mystery. The obvious choicesome sort of sliding plastic assembly for the lenseswould add more weight to an already component-crammed headset, Luckey says, and it can get gritty, it can get locked up, and it isnt comfortable. Instead, the lenses are seated in a taut layer of flexible fabric that he calls transformo. Behind the fabric is a tiny dual rack-and-pinion mechanism that adjusts the lenses distance from one another. The fabric is dustproof (to protect the mechanism), transparent to infrared light (so as not to interfere with tracking), and does away with all the complexity and weight of a more obvious solution.