The Medium Intermediate sinks at 1.5-2 Inches Per Second and features two hang markers at 14ft & 24ft. Hang markers indicate when it’s a perfect time to hang your flies. An aggressive density compensated taper design allows flies to properly sink to effective depths.
How to choose your line ?
The Cortland competition fly line are double numbered and don't take this as a fancy reference to DT or WF... They are lines with a WF profile.
So the double numbering 6/7 or 8/7 will depend on the recovering and power of your rod:
Rod in #6 fast action choose the 6/7 model
Rod #7 medium fast or progressive action choose the 6/7 model
Fast action #7 rod choose the 7/8 model (Cortland rods in #7)
#8 medium fast or progressive action rod choose the 7/8 line. version)