Inline Air Filter 3-Pack: AI303 150 PSI Oil and Water Separator

3 LE LEMATEC AI303 inline air filters in one order. Put one at the compressor and one at the tool, one at each work station, or keep spares on the shelf. Bought separately, 3 filters cost $50.97.What is in the pack 3 x AI303 Inline Air Filter: 2 to 150 PSI, 1 micron filter, 1/4" NPT, aluminum body with brass fittings, push-button drain ($16.99 each on its own)Shipping: Free shipping on every US order. Ships from Amazon fulfilment, so parts may arrive in separate boxes.QuestionsWhere should the filters go? One right after the compressor tank catches most of the water and oil. One right before a spray gun or air tool catches what forms in the hose.How do I empty the water? Press the push-button drain at the bottom of the bowl.