The Rig Mount (RM-705) is for mounting the ICOM IC-705 transceiver and AL-705 magnetic loop antenna on a tripod. It can screw on top of a tripod’s male 1/4 20 thread.
An optional accessory, the TM-705 (Tripod Mount for the AL-705 antenna) can install onto the bottom of the match box, which would then enable you to install the AL-705 antenna onto the RM-705.