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

 - Coil Material: 316L Stainless Steel (304, 321, etc. Stainless Steel available to order)
 - Inner Coil Material: Copper
 - Tubing Dimensions for Inner and Outer Coil  (O.D.×Thickness, in./mm): 0.375" × 0.020"/ 9.52mm × 0.5mm
 - Coil Dimensions(Coil O.D x Length x Turns in./mm): 9" x 12" x 40 / 228.6mm x 304.8mm x40