An endoscopic portal for establishing communication with a body cavity for the introduction of instruments through the endoscopic portal includes a seal having a variable size passage for communication with the body cavity to permit instruments of varying sizes to be passed therethrough and a tubular...http://www.google.se/patents/US5989233?utm_source=gb-gplus-sharePatent US5989233 - Endoscopic portal having a universal seal and methods for introducing instruments therethrough
