What is Class E3 airspace?
It looks like its an extension of Class C Airspace from a class E3 announcement, 


  ...Class E3 airspace areas are designated as arrival extensions to a
  Class C surface area. Class E arrival extensions are primarily
  designated to provide additional controlled airspace ancillary to a
  surface area to protect instrument operations for the primary airport,
  without imposing additional communications burdens on airspace users.