The company behind Permatex also make Versachem products.
Versachem also make a flowable windscreen sealant, the data sheet shows the contents to be almost identical to Permatex. I talked to the company. They said they are almost identical but that Permatex is a little thinner, more runny . The Versachem is also cheaper
Put item number 121857314531 into eBay search bar .
We used the Versachem flowable on the feet of our Piper doll TPE and it worked a treat , the bond is strong and remained soft and flexible once cured
Not used Versachem on silicone yet but Wacker E43 was excellent on our Sanhui