I have used Jetseal, it is a Sealant and should be used after polishing as a Last Step Product (LSP) and it will be cracking. Two coats as a LSP works well the first left on the car for about 30 mins then buffed off then the second applied and again leave for thirty mins then buff off the finish should be good and the protection it gives lasted me for about 5 months.

Cheers

Billy