A specimen testing device having a first panel with at least two apertures, a second panel with at least two apertures opposite the apertures in said first panel, a sheet disposed between the first and second panels for receiving a specimen through the apertures, the sheet in the apertures in said first panel having first, second and third portions disposed on opposite sides of a longitudinal axis of the apertures. First aperture covers are mounted on the first panel and overlie the apertures in the first panel. Second aperture covers are mounted on the second panel and overlie the apertures in the second panel. The first and second aperture covers in the first and second panels are movable independently of each other to expose the first, second and third portions of the sheet.