The 8 diameter 108 4-PRO is a special clutch for the racers and the really hiperformance oriented snowmobiler. The four post design sets this clutch apart from the rest. 4-PRO is balanced to almost dead zero, the faces are turned for smooth performance. Four post technical advantages: greatly enhances tuneability, eliminates tower spreading, roller and button life is increased. 4-PRO clutch uses the same cam arms and springs as the 102C and 108EXP models.