A soldering iron adapter for one type of the ceramic center post solder irons. End is threaded to 8/32 female to fit all of our tips. There are many different designs, so measure and make sure this will work for your iron. This works with irons that utilize 900M bits. To the best of our knowledge, this includes 900M, 907, 913, FX-600, FX-8801. Center post hole (that the ceramic element slides into) = .156" diameter, 1.02" deep. Total shaft diameter: 0.25" Total length from base to shoulder: 1.075"