Yes it's marketed as a caulk and it works perfectly for that. But as a flexible glue it is absolutely the best. It sticks to basically anything, and I mean sticks. It's waterproof, VERY flexible even when a few years old. I use it to repair shoe and boot soles, it's much better for that than Shoe Goo which turns yellow and hardens and peels off after a couple months. It sticks as a glue MUCH better than any other caulk. It's much stronger and tougher physically as a glue. Yes silicone stays flexible but it's a lousy glue. It stays flexible and doesn't crack like almost any other glue.