The DiversiTech® D61280300 line set is designed for air conditioning and refrigeration systems. Size is 3/8 in. insulation wall, 3/4 in. suction line, and 3/8 in. liquid line. The suction line is pre-insulated with Armaflex AP pipe insulation. The insulation is a black flexible elastomeric thermal insulation. The expanded closed-cell structure makes it an efficient insulation.