This is a case of 25 new, clear polystyrene (plastic), non-graduated 17mm (17OD & 14ID) x 150 mm (approximately 6 inch) test tubes. The test tubes have a liquid storing capacity of up to 20ml . They are non-sterile and come with a translucent Flange Cap, which insures a good tight fit. These precision-molded test tubes are ideal for a wide range of laboratory applications. They are made of a clear plastic resin, thus preventing the problem of broken glass. Since polystyrene is not as hard as glass, however, it can scratch easily, especially during shipping. This will not affect the use of the tubes, however. So please be aware that your tubes may have some minor scratches or scuffing that should not show when filled.They have a number of applications outside of the laboratory, including invitations and weddings. They are great for storing anything from beads to small saw blades. Includes a pack of 25 translucent Flange Caps. Colored Hollow-Top caps are available upon special request; generally in white, green, lavender, yellow, orange, red or blue. Sorry, only one color cap per order item. Please call or email us ASAP with color preference if you desire a colored cap. NOTE: Neither the test tube nor the caps are autoclavable.