2 x 7 Speaker / Subwoofer Replacement Spider. Some of the models that use this spider include : Any requiring a 7" spider and a 2" voice coil. Inside Diameter - 2"; Outside Diameter - 7"; Stiffness - "C" on a scale of A-F (F is the stiffest); Inner mounting has 3/16" tall vertical lip to hug the coil former. Stacking is not recommended. Spider - FS-D