The straight walls allow use of metal or plastic caps. We supply these tubes with polyethylene KimKaps which fit via internal plastic ridges which insure an air supply. We suggest beginners wrap the tubes with plastic wrap. To save the labor of washing, professional labs discard these tubes after a single use. Amateurs can autoclave the used tubes, for safety, and then wash and reuse them.
Diameter is nominal outside diameter.
Due to the thin walls some breakage during use and shipping may occur. We mostly use the 16 x 125 mm size. Personal checks accepted, whether we must wait for check to clear depends upon how well we know you. We welcome inquiries. We are not set up to accept credit cards.