This element has great mid-tones, and gritty, mild lows. The 99S556 elements came stock in Shure 520's and are super-strong why high output, 1225 on this one.
The face of the element still has glue from the original owner. I don't like to remove the glue, because the solvents can also remove the bobbin adhesive. And the glue doesn't effect the sound, so I leave it alone. I've left the wires on, ready to hook up and install.
Manufactured: January 1981
I've personally tested this element in a Shure Green Bullet shell and played it through a Kalamazoo Model Two, and custom Mission Chicago Harp Amp.