This is a helical coil heat exchanger used in indirect water heater. 

 - Material: 304 Stainless Steel (316L, 321, etc. Stainless Steel available to order)
 - Tubing Dimensions (O.D.×Thickness, in./mm): 1" × 0.04"/ 25.4mm × 1.0mm
 - Coil Dimensions(Coil O.D x Length x Turns in./mm): 6" x 12" x 20 / 152mm x 304.8mm x20