Polypropylene tubes to hold 1-4 slides. Can be used to mail slides and to store small numbers of slides. Also these mailing tubes can be used as miniature Coplin jars to dip slides in photographic emulsion for autoradiography. The advantage of using these jars with emulsion is that they require only a small amount of emulsion, they are disposable, and you don't have to worry about cross-contamination from one batch of emulsion to the next.