Regarding correct size for your engine/boat. This is something the prop manufacturer will probably have on their database (especially for a high production model like the L380). 'Flex-o-fold' props are made in Denmark
I believe, but we purchased ours through a UK distributer (Darglow engineering) as they were able to machine match the bore of the new prop exactly to the bore of our old prop (which we sent them in the post) etc. It was 'Darglow' that matched the folding prop size and pitch
to our engine and boat (a Westerly Konsort 29')
We purchased ours in 2012 and the price
then was around £850 (UK sterling) for a single 2 blade
. Not cheap
, but even my wife agrees it was worth it as the difference in performance is very noticeable.