The Metal Sonic Mask is a sinister looking mask crafted by a mechanical genius whose ability is said to rival that of even the greatest gremlin Gear Sages. 
Combing it with the Metal Sonic Suit unlocks Metal Sonic.
The Metal Sonic Mask is a sinister looking mask crafted by a mechanical genius whose ability is said to rival that of even the greatest gremlin Gear Sages. 
Combing it with the Metal Sonic Suit unlocks Metal Sonic.