The Alkin is the best portable High Pressure Breathing Air compressor made for the money.  These are the most powerful, durable and quietest portable compressors made. CGA G7.1 E quality breathing air. The ALKIN W31 is the only portable compressor factory approved for filling cascade systems and multiple tanks.  Alkin also sells 444 cu. ft. cascade bottles. It does NOT void the warranty to fill these Cascade bottles. The ALKIN comes complete, tested full of oil and ready to run. Available in gas or electric power.  This compressor runs at 1200 RPM for the coolest and quietest compressor in its class.  This compressor has a 5000 PSI max with a working pressure of 4600 PSI. The purifier is a refillable type that saves you money.  With Alkin you will get the most powerful compressor, best shipping prices and we do not exaggerate our CFM performance.  All of our compressors are designed to be durable, easy to work on and parts are readily available at a reasonable cost. This gives you a compressor that can last a lifetime and not a "Disposable" compressor. We stand behind our warranty and our products.