Discmania says this about the MD4 Midrange: This disc is the overstable brother of the MD3. The MD4 has a blunt nose with that standard MD3 micro-bead giving it a familiar feel in the hand. Not only is the MD4 overstable, but it also has a surprising amount of glide, allowing your shots to fade more while still maintaining predictability. Whether you're facing a stiff wind, looking for a controlled hyzer line, or throwing a nice touch sidearm, the MD4 has you covered.
About Stiff P Line Plastic
Stiff P Line: Great feel and added glide. Easily one of the grippiest plastic type out there. Reveals new features in your disc when worn down. Typically a bit more understable plastic type comparing to S- and C-line. All the benefits of regular P Line, with a feel and rigidity that is noticeably stiffer than the usual P Line blend.