which ones for slush casting?

so i get to the smooth-on web site, and i look up the stuff for making molds/casts, and i find a huge list talking about stuff like viscosity. i have no idea what-so ever which product to purchase. can anyone help me out. i need stuff for making the mold, shell, and which stuff to use for slush casting.

thanks.

I use:

Mold Silcone - Brushable 25
Casting: Smoothcast 300 fast (not quickset mind you)