1/2-13 X 1-3/4" Cad plated flat head socket screw. This screw replaces part 1FSTNR-FH839. Used On: Current style exit trap door.Trap door kit (CV 105186) Gyro Bearing Retro Head Assembly Gyro Bearing Base Head Assembly 3L Electric Flex Boom Assembly 3LW Hydraulic Flex Boom Assembly