Get current pricing for Koch Membrane Systems, 4-inch 30-50 gpm RO Koch 4 30-50 Gpm Ro With 7:2 (4-3m, 4-4m: 2-3m, 2-4m) Array (42 Membranes). First Stage Consists Of 4-3m And 4-4m 4 Codeline 300 Psi V . Product Category: Process Equipment, Sub Category: Reverse Osmosis Equipment: