1104 is good at sealing and resistant to most things, but the nastiest thing to use. Usually end up with it all over the place.

1207B is much nicer, and HRC use it. On the downside it's a lot lot lot more expensive. If you only intend to use it every now and again then go for the cheap option.

Whatever you use, make sure the case is spotlessly clean and free from any oil/grease or it won't seal.