Integrated hinged inserts. Use with R-134a, R-12 and oil charge cans. High impact HDP composite construction for durability. 1/4" (R12) and 1/2" Acme (134a) fittings for versatility. Eliminates the need for 3 separate tools This unique new design makes servicing A/C systems with 12 oz. cans of R12 or R134A refrigerant (and 4 oz cans of oil charge) faster and easier then ever before. One tool for 3 different diameters of cans.