This is a pack of 72 clear new glass test tubes, industrial grade . This is the most common size test tube used in laboratories. They are borosilicate glass (heat resistant). Size is 16mm x 150mm (6 tall) and hold 25ml. The opening has a slight  rolled lip. Size is given with  OD (Outside Diameter) first then length. All measurements are approximate. OD measurement may vary by up to 1mm.

The rubber stopper that would fit this size opening is a Size 0. The cork stopper size is #4 or #5 cork, depending how far you want them to go in the test tube. They would be great for students, teachers, labs, crafts (even holding beads) or for decoration. Many people feature these as vases; they hold one or several blooms.  pk of 72.