Assertion: flipper | /r/HasProperty | provided with blade
Facets:
Source sentences:
text: It is known about the existence of flippers provided with blades which can be rotated of a certain angle with respect to the sole, and which are connected to front protruding elements of said sole by means of side extensible elements, which, during the passive flipping, stretch out and allow to vary the inclination of the blade with respect to the shoe and to the sole under the action of the water acting onto the back of said blade, so as to ease the diver's movement.