Alva-Line isometric tracing paper, drawing paper. Printed in a non-reproducible blue ink on Alva-Line blue-white quality 11" x 17" tracing paper, the isometric grids are clear, sharp, and accurate, yet will not reproduce on Diazo prints. All grids are printed on the underside of sheets to prevent removal during erasure. These medium weight, 16 lb. basis, .00275 thickness, pads are ideal for use by engineers, draftsmen, architects, graphic artists, etc. 50-sheet pad. Alvin 6855ISO-7 Alva-Line isometric non-repro tracing papers are made in the USA.