Assertion: flipper | /r/HasProperty | costly
Facets:
Source sentences:
text: The complexities of some of these units and the requirements that the units be made of combinations ofvarious materials or have operable mechanical elements result-in swim fins. or flippers-which are subject to breakage, which do not operate properly at all times, are costly, and appear to be inefficient, cumbersome, and difficult to wear or use.