An improved endoscope of the variety which includes an endoscope slideably nested inside of a guiding tube, including an improvement that renders on demand either the guiding tube more flexible than the endoscope or the endoscope more flexible than the guiding tube. The improvement may be one of several...http://www.google.com/patents/US4815450?utm_source=gb-gplus-sharePatent US4815450 - Endoscope having variable flexibility
