PTFE-coated, octahedral, with pivot ring. High turbulences because of its angular surface, even at a low number of revolutions. For vessels with slightly uneven ground. The pivot ring reduces the supporting surface and detects its optimal rotating position on its own. PTFE-coated, octahedral, with pivot ring. High turbulences because of its angular surface, even at a low number of revolutions. For vessels with slightly uneven ground. The pivot ring reduces the supporting surface and detects its optimal rotating position on its own.