Manufactured using virgin polypropylene, verified for leachable metals by ICP-MS. Low leachable catalytic/additive metal content, excellent visibility and good acid resistance are guaranteed. Tubes are graduated, in 5 ml increments, up to the 50 ml graduation mark. The 50 ml graduation mark is certified accurate to ±0.25 ml in accordance with ASTM Class "A" volumetric standards. This reduces and eliminates the need for graduated cylinders and volumetric flasks.