This collet type aluminum Prop Adapter fits 2.0mm motor shafts, and has a 4.3mm x 1/2" shank. It works well with APC 'slow fly' props and the smaller APC 'E' props. The larger APC 'E' props are a marginal fit on this adapter due to their thicker hubs and the relatively short shank on this adapter. APC props usually include a 4.3mm adapter bushing that allows them to fit this adapter shank.
GWS props will have to be drilled out to 4.3mm (11/64") and the hubs filed down on the larger sizes in order to fit on this adapter.
The conical prop nut on this adapter has a hex edge, so the nut can be tightened or loosened using a small wrench.