Why we use this type of rivet:
The Bullfrog Rivet is an aluminum shaft, enclosed rivet with a steel mandrel.
The steel mandrel is necessary to insure a high pop rate, intended to maximize the expansion of the rivet. Hence, the steel mandrel insures a tight seal within the cavity.
Once the sealant coated rivet is popped, the mandrel separates and a small steel ball within the rivet remains. Using the provided poly brush, wipe the bead of sealant that surrounds he rivet head and insert the sealant into the cavity seen on the rivet head.
This pliable dab of sealant seals in the steel ball and prevents corrosion from becoming an issue.