It can transform the wielder into any alien from the Omnitrix.
The Biomnitrix is two Omnitrices that are linked together, thus allowing the user to perform alien fusions by slamming the two gauntlets together. These fusions are not stored in the Biomnitrix, rather, they are created when being transformed into.[DJW 2]
By using just one gauntlet, the user can transform into normal aliens.[DJW 3]
It can be voice-controlled or even used without actually having to say the name of the alien, similar to the Omnitrix's Master Control.
Compared to past models, the Biomnitrix is incredibly streamlined and lightweight, possessing practically no bulk and appearing to perfectly blend in with, and mimic, the natural curves and contours of the user's forearms.
Ben 10,000 created the Biomnitrix with the minds of his smartest aliens.[DJW 20]
It is just like how the first Ben 10,000 used his smartest aliens to create the replica Omnitrix he made for his son.
Azmuth thinks the Biomnitrix is silly, but ultimately he's just relieved that Ben is having fun again.[DJW 21]
All Way Big fusions are smaller than Way Big, unless he is fused with something of the same size or bigger.[DJW 22]
When the Biomnitrix times out, the sounds of the original and latest Omnitrixes' respective time-out clips play simultaneously. However, since its Master Control is active, the Biomnitrix would only time-out if Ben suffers severe damage. It also timed-out after the erased-of-existance Atomix-X was restored via the use of Clockwork's powers.
Out of all the concept ideas, XLRG was the only one that was drawn. The others were 'names on the board'.[DJW 11]