1.2" Double female.
There is not enough area unthreaded to support having threaded holes added to these. In order to make this as short as possible it was designed with one side threaded to work like any standard female MHS section while the other side is threaded just deep enough for the male threads.
All MHS parts should have the threads wiped clean and then lightly oiled or greased. We sell some
Synthetic Grease for this. Parts that get stuck because no oil/grease was used or that are damaged by the user trying to take them apart will not be warrantied.