If you are working with air or water, in pneumatics or hydraulics, then our compression and airline brass fittings are just the right thing to cap off or join threaded connections, create junctions within pipework or tubing, or extend pipework.
You could choose to make a tight seal with pipe or tubing by using more modern quick connect or quick release fitting, but if you're someone who likes the old school, proven ways, then brass compression fittings are going to give you a super sturdy and solid connection.
Create a water or air tight seal with just a few parts, connecting them to your pipe or tubing: the fitting, the sleeve, and the nut. Pair with tubing of any material and connect a water line for hydraulics, or an airline or gas line for pneumatics work.
The good thing about brass, especially with pneumatics, is that brass will take heaps more pressure than plastic fittings, even those that come with stainless steel sleeves. The solid nature of the connection with brass compression fittings means you're probably getting the best possible fit you can for your purpose.
If you are replacing a connection, plastics are more prone to leak so either choose brass from the start or fix your leak with brass materials. As with any connection, a key factor is making sure the connection was closed down tight enough, but with brass you might not have to replace all the parts or the fitting, you might only have to re-seal it. With plastic, you'll find a more likely issue is the nut has backed off or cracked.