Finned tubes with collars, The collar that I have labeled in the picture is made of close packed fins on the tube. The collar is made out of fins. If you look below you can see what I mean. The fins are far apart then when you get to the collar the fins get very close together to form the collar. Please see the pictures below:
The other characteristics of the tubes we need are as follows:
-Fin material is copper
-Tube material is stainless steel or 90/10 copper nickel
-The entire tube is coated with lead free tin solder to connect the fins to the tube
-Tube sizes we use are 1/2 inch up to 1 inch. 5/8 inch, 3/4 inch, and 7/8 inch are the most common tube sizes
-Tubes are 18 or 20 bwg wall thickness.
-The height of the fins are 1/8 inch or higher.