I installed some 1/2" Liqua flex the other day for the first time in my career....those fittings are junk. I was using this stuff to cover up some old sun beaten NM that had been installed on the back of a house next to a service. I stripped off the crusty NM sheath and fed the wires through those fittings....not much room inside the fittings in relationship to the raceway size.....It sure wasnt 40% fill !!!!