What's this part for

Ok that shaft is ment to add length to your ase part of the antenna..It gets that plastic piece(load coil)higher up which is a good thing..So just take off the short one and add longer one..
To test swr you will need a seperate meter ment for that test,a jumper(coax and length makes a difference)...Nothing to do with the mic...All tests are done with radio portion..