Pack of 3 filter cartridges for replacement in filtering system to help preserve the life of your pump and increase the performance of your freeze dryer. First use: Remove cartridge packaging, grip the top of cartridge and place into cartridge holder of Harvest Right filter. Firmly press in cartridge until it makes a firm seal. Cartridges should be replaced after approximately 15-20 uses, or sooner, depending on the quality of the oil. Oil Filtration Directions: 1. Open the oil reservoir drain valve and allow oil to drain into your oil filter. Assure all of the oil comes out by lifting the rear of the vacuum pump slightly. 2. Wait for the oil to filter through your filtration system. 3. A small amount of water accumulates in the oil as part of each batch. When the oil is filtered, the water and oil will separate. The water will sink to the bottom of the bottle while the oil floats on top of the water. 4. Remove the water from the oil by pouring o the oil and discarding the water. Do not pour the water back into the vacuum pump. This will ultimately damage the pump. 5. Pour the filtered (or new) oil into your vacuum pump. How do I know that my filtered oil is clean for use? The best indications for cleanliness are as follows: Oil is void of debris or particulates Oil is not milky or chalky Oil has clarity (the color may be yellow or amber and still have clarity) Your vacuum pump is achieving a pressure (mTorr) suitable for freeze drying. How do I know when I need to replace my oil filter? Oil won't drain through filter (this can happen over time as debris builds up) Oil isn't cleaning well (i.e. The oil continues to be milky or full of debris)