Compact-box design made of ABS plastic steel so it can't rust and easily install. Moreover, it can block insects and dust effectively. With 2.2 GPD built-in tank it doesn't take too much space. Membrane housing with double o-ring design and has passed 100,000 times strict cycle testing under 150PSI water pressure and 300 PSI burst test to make sure it's durable. All pass NSF test standard. 100% pure raw materials for spare parts contacted water. Before shipment all pass 100% leaking test. Made in Taiwan.