For years I searched for such a piece.  It is superior to hose in hose or coil in coil designs because of 3 things:
1. Build Quality: Stainless steel means no corrosion and no leaks... EVER!
    2. Surface Area: Heat transfer depends on surface area. This unit has the same surface area as a 15 foot heated hose BUT with superior flow rate:
    3. Flow Rate:  Full 1/2" MPT connections means you can run 3/4"ID heater hose and get full flow rate. More flow equals more heat transfer. Also, consider this: all the tubes are in parrallel which means that it takes 1/15th as long for the coolant to travel through the unit as a heated hose or coil. This is why they are so much more efficient and the design that is used for industrial heat exchangers the world over.
    Available in longer lengths for larger engines... or just stack 2 and save money!

Price: $250.00