These 2mm thick clear acrylic covers are included with every purchase of the Leviathan fight stick. You are free to purchase more to use as a replacement or spare. The acrylic cover not only dampens the sound of button presses, but it can also be used to install custom artwork to your case.
The Japanese variant features a 24mm hole for levers from Sanwa, Seimitsu and low collar Korean levers. The Korean variant features a 35mm for full collar Korean levers.
Note: The acrylic cover will be shipped with a protective film on both sides. You need to remove this before use. There may be 1 or 2 small white / black speck(s) on the acrylic. This is normal and a side effect of the acrylic manufacturing.