Rigid Nipples with Insulated Throat Zinc Die Cast 4" - Rigid Nipples are Used with Rigid Coupling to Terminate Threaded Conduit to a Knockout, Box or Enclosure, where space is limited within the box.Rigid Nipples with Insulated Throat 4" features include: Use with Rigid Coupling to Terminate Threaded Conduit to a Knockout, Box or Enclosure, where space is limited within the box Use with a Locknut to provide a Short Raceway between Boxes and enclosures Insulated Throat Die Cast Zinc UL/CSA or cULus Listed Order Qty of 1 = 1 Pieces Below is more info on our Rigid Nipples with Insulated Throat 4"