Oblong as an anti-tank rocket, drilled ventilation holes / flow like the latest generation of suppositories, this system has resulted perfectly drains from my sister in law (well of his house, we understand) that were most need. More untimely delivery of remugles smelly, non ecological compost ... No it opens REALLY .... And that is considerable seen what we read in magazines as serious as "plumbing all-HS -The DIY tips Namuroises-Editions "(out number) ...