This adaptor has been designed to adapt the factory fitted 7mm male thread on new Volvo FH.4 to a 3/8 antenna fitting.
This will allow you to fit a 3/8 antenna to mount such as springer/stinger, red thunder modulator and other 3/8 fitting antennas.
Please note this is a 7mm adaptor for Volvo FH.4 not a 6mm unlike most Volvo mounts.