Help: What Sealant Should We Use on a Toerail?

[BettiedelMar]

We are working on sealing the top edge of our aluminum toerail, and we're kind of confused about which sealant to use. Should we use 5200, which is what 3M says? Or should we use 4200, which other folks have suggested because it's more flexible? Thanks so much for your advice!

[feelsgood]

3M™ Marine Adhesive/Sealant Fast Cure 4000 UV this is the best you can buy. Regards Pete