or its transmission cable 32 to provide a tight sterile barrier this end remains sealed at all times during the operation the opposing end 34 of covering 28 is associated with the coupling 14 in the manner described below in the embodiment illustrated in fig2 end portion 34 of covering 28 is disposed within a cavity defined within coupling 14 as better shown in fig4 7 end portion 34 is disposed within coupling 14 and underneath flared end 18 of endoscope 12 rollers 16 are covered by end portion 34 and when actuated clamp end 18 and press end portion 34 tightly against flared end 18 of endoscope 12 end portion 34 is positioned on coupling 14 and registered with respect to the endoscope to camera optical path by means of a resilient elastomeric ring 36 which is coupled or fixed to that portion of covering 28 which overlies the circumferential portions of coupling 14 and in particular the ring 20 referring now to fig2 and 5 elastomeric ring 36 is adhered to covering 28 and circumscribes end portion 34 which fits into cavity 15 and against the annular base of the cavity 15 defined by coupling 14 end portion 34 has an aperture 38 defined therein.