Our all new SHB-595A Water Vacuum Pump uses water to pull a vacuum. It requires no oil what so ever to operate, allowing for a low maintenance, easy to use vacuum pump. Each vacuum port pulls vacuum separately allowing for either separate applications or connect them together for a stronger vacuum. This pump can also be used to re-circulate water through the back ports if needed. These work great for our 10L, 20L and 50L Rotary Evaporators and are an inexpensive yet effective way to pull vacuum! For Technical Support, Questions, or Other Issues Please Email or Call Us!