Galvanic Zinc 7-Day Timed Release "Pop-Ups" (5pk)

Galvanic Zinc 7-Day Timed Release "Pop-Ups" (5pk) Galvanic Timed Releases (GTR’s) are reliable underwater timing devices. They are also known as POP-UPS. The patented design of the GTR uses two dissimilar metals that corrode at a predictable rate. GTR’s must be used in salt water. Their corrosion rate depends on the water’s salinity and temperature at the depth being used. GTR’s release t