Power Assisted Swimming
These are gauntlets or other swimming suit pieces based in this principle, that allow the swimmer to increase the surface area of the arms on the propulsive pull stroke, and which tuck snugly against the arms on the forward reach stroke, and so reducing the hydrodynamic profile of the arm on this later stroke... alternately increasing and decreasing the resistance in the water so more of the effort applied goes to pushing the water backward, and moving you forward than is cancelled by the reach strokes.
The gauntlets are an assembly of elastic vents like gills around the forearms which, when you reach froward, close up due to the water pressure outside the vent moving over it, but which, when you pull, the water resistance opens them up like a sock, or mini parachute, gaining you more traction in the water, so you crawl through the water with more “bite”.