Assertion: flipper | /r/HasAspect | heel surrounding portion
Facets:
Source sentences:
text: 2, 3 and 6 that the two-piece flipper is composed of a shoe (1), having a heel portion, a fin (2) having a front portion and a heel surrounding portion, in which a hole (8) having an area larger than that of the said heel portion of the shoe (1) is provided; on two sides of the said fin front portion there are upwardly protruding and symmetrically disposed protruding strips (21)