Nebulisers turn liquid medication into a fine mist that is breathed in through a mask or mouthpiece, and are used at home, in clinics and in rest homes under the direction of a prescriber. This is a compact section: one device and the consumable parts that go with an existing unit.If you are buying the machine, the Portable Ultrasonic Mesh Atomizer is the option here and is sized to be carried. The other two listings are parts for the Nebuliser 501, a Replacement Masks Set and a Medicine Cup. Both are wear items rather than one-off purchases, since masks and cups are handled and cleaned repeatedly and eventually need replacing, so it is worth having a spare set on hand.Parts are model specific. Check the marking on your nebuliser before ordering, as the 501 masks and cup are listed for that unit and are not a universal fit. Follow your prescriber's instructions on what to nebulise and how often.