This adaptor is made of two pieces: a 5/8"" bushing with a 3/8"" female attachment to connect it to a tripod and a removable plate 124mm diameter with a 5/8"" male thread that should stay connected to the equipment.
With the 324 it is possible to transform any Manfrotto tripod into a tripod compatible with the standard attachment interface system used in the survey and measuring industry.