... /2", 3/4", 1"2. QAC- F.R.L (Three Combination) (1) All Models: AC2000-01, AC2000-02, AC3000-02, AC3000 ... -02, AC4000-04,AC4000-06, AC5000-06, AC5000-10(2) Metal Protective Hood: AC2000-01, AC2000-02 are not ... Type AC2000-02 Air source treatment Unit (F.R.L Combination)