Abstract: A wrap ring assembly comprising a pair of wrap rings for accommodating an engagement or other ring therebetween is provided. The wrap ring assembly includes a first ring having a first band and a second ring having a second band spaced from and substantially parallel to the first ring. The rings of the assembly are interconnected by a pivot assembly which enables the bands to revolve about a common axis that is tangent to the periphery of each of the bands.

Abstract: Disclosed is a medical cannula or amniocentesis needle of improved sonographic visibility. The invention comprises a needle or cannula having one or more sounding apertures formed therein. The diameter of each sounding aperture is substantially equal to a predetermined wavelength of an incident ultrasonic beam. As a result, the beam will diffract upon striking the sounding aperture and the resultant echo will diffuse isotropically therefrom, thereby improving the ultrasonic detectability thereof.

Abstract: Disclosed is a medical cannula or amniocentesis needle of improved sonographic visibility. The invention comprises a needle or cannula having one or more sounding apertures formed therein. The diameter of each sounding aperture is substantially equal to a predetermined wavelength of an incident ultrasonic beam. As a result, the beam will diffract upon striking the sounding aperture and the resultant echo will ddiffuse isotropically therefrom, thereby improving the ultrasonic detectability thereof.

Abstract: A substrate transparent to x-rays mounts a resilient layer transparent to x-rays, and an overlying thin blocker layer of fracturable lead or tin foil which is opaque to x-rays. When impressed or typewritten the blocker layer is selectively stenciled or fractured to permit selective passage of x-rays therethrough. The substrate or a perforated portion thereof mounting the stencil, is emplaced upon an x-ray cassette during x-ray exposure to capture the stencilized data in the permanent film image. Visual inspection of stencilized data may be aided by a white paint layer disposed upon the blocker layer. Affixation to the film or cassette may be aided by a pressure sensitive adhesive layer in an area adjacent the other superimposed layers.