I'm about 5'6 and 105lb so I'm on the small side. I ordered both A/B and C/D just because I ordered some tights before (XS but not from this brand) and it was a little too tight on my feet because of my height. I tried the A/B which is just as expected - about mid thigh length and it fits quite well but... you have to take into consideration the top silicone band which takes about 2inches of the length. So if you plan on wearing something mid thigh then this one is going to be a little too short because you don't want the anti slip silicone top show out, right?! I tried the C/D as well and it fits good as well. I can easily pull it up to the top of my thigh (but I can also make it less tight by leaving it at mid-thigh length). Obviously on me, size C/D is more black than A/B and the silicone band is a bit bigger but you can still kind of see through the knee when flexing your cuff (there's no noticeable difference on bending knee part when choosing AB or CD), as to the silicone top I am not quite sure as I have not wore C/D for entire day to test it but when I tried it walking in the house it stayed (I'm usually 0 or XS, or 24/25 and I have slim legs). Overall they both work fine and I kept both because I'm afraid they will not produce these anymore (You know how it works: they almost always have to discontinue great product for some reason).