The Vahi - Mask of Time - as interpreted by me from official art. The mask grants the wearer visions of the future and the ability to tap into the power of time. It was designed to be worn along with the official lower-half Kanohi of Time. So far, I've only tested with Strong & Flexible Polished.
NOTE: THIS MASK IS ONLY DESIGNED TO WORK WITH 2001 BIONICLE HEADS. THE MASK WILL REST LOOSELY ATOP THE HEAD. YOU NEED TO PUT ON THE LOWER-HALF KANOHI OF TIME TO PREVENT IT FROM FALLING OFF WHEN JOSTLED.
To put the mask on, carefully set the mask atop a 2001 Bionicle head. It will fit loosely, but should stay if you don't jostle the mask or the figure. Next, you will want to carefully place the lower-half Kanohi of Time over the upper-half as usual, except you don't need to push the lower-half mask all the way into the mouth. You should be able to get both masks fitting snugly together, without either one being loose.