MKID dual layer switch film is a two-sided switch film with both HTV and PC material. With the thickness of 0.15mm, the films will fit most switch types. Each pack comes with 120 films which will cover a full size keyboard with extras. These films close the gap between top and bottom housing to ensure a tighter fit of the two parts. The result is a bassier sound, and more importantly, less wobble of the top piece. We recommends installing the switch films with the HTV (matte surface) facing lower/bottom housing and the PC (transparent surface) facing the upper/top housing.