Sorry, Oly! I kind of flew through here and did not think about the TC thing. It is temperature control. Your IPV4 is capable of controlling the temperature rather that using watts or voltage. Key is that you must use Nickel or Titanium coils in temp control mode. With TC, you will never get a burnt or dry hit and the juice is kept at optimal temperature.
I get my regular coils here
Kanger Subtank OCC Coils - $12.95 - WORLDofVAPE
But, as you know, sometimes coops have better pricing

I also found a vendor with good pricing on the nautilus and kanger nickel coils. Let me look and see where I got them and I will post a link.