I have some similar to those. The outer part is 2 pieces, bobbin is inside. There is a pin or rod through the center and a push type lockwasher holds it together. I've seen some with a bolt through the center. 38 gauge wire i think. You usually crack them if trying to take them apart due to the sealant being like a epoxy type. I have a bunch from some WE (telecomm?) equipment in various values i was trying to take apart to rewind and remember cracking them either taking them apart or reassembling them with a bolt. You tighten the bolt the inductance goes up, adjustable, sort of, until it cracks.