This item is a 6 Spoke 3 5/8" Wide Diverter Knob for a 1" Waterfall or Neck Jet Control..
The outside measurement is about 3 5/8" and the center hole is about 1/2"..
NOTE: There is an Air Control version of this know that measures about 3 1/4" wide with a center square that is about 5/16" wide. This cap and that cap are not interchangeable..
