The Ultimate DQ500 DSG / S Tronic Transmission Catch Can and Breather System is here! The factory transmission features a plastic breather system that allows for transmission fluid expansion and removal of gases. Unfortunately, this system easily becomes taxed, causing transmission fluid to spew all over the engine bay. The APR system fixes this problem through the use of an easy-to-install and compact catch can system. The larger can collects the expanded fluids and allows for venting of trapped gases through a breather filter. The can is larger than stock and fluids enter at an angle to help prevent the fluids from spraying through the breather filter. When possible, the transmission fluid simply drains back into the transmission.