BEADSMITH SHINE RITE Anti Tarnish Tabs Strips 50 1x1" Tarni-shield USA Right

From the manufacturer:  These tabs have approximately 2 years shelf life after put into service (taken from the manufacturer's packaging).  We have reports from many customer who have had these last 5-7 years.  Keep enclosed tightly when not in use to extend the shelf-life.  Just place in a resealable bag.

These are the newer, thicker version.