WW2 German EK1 Iron Cross 1st Class Screwback Unknown Maker

Original ww2 German EK1 screwback with private purchase mounting in good condition. No maker mark, and with research to the best of my ability, can’t pin down a maker. 3 piece construction with magnetic core. Screwback mounting is 3 piece with a non threaded disc and threaded cap that keeps tension when put on a uniform – on its own, the disc isnt snug against the back of the medal.