Abstract: Method and apparatus for testing open ended containers wherein the open ends of the containers are clamped against regularly spaced apertures in a carrier wheel and are rotated along a locus leading across two spaced inspection stations. Lighting is provided principally along the container sidewall leading with respect to the direction of its locus of movement within the first inspection station environment and is provided principally along a sidewall considered lagging as the container passes the second inspection station. Defect responsive photosensing signals from the two stations are submitted to OR logic sequential memory to syncronize the operation of a discharge carrier. No vacuum retention of the containers within the transfer disc region is required.