I just received a 3 gal. Rubbermaid mash tun kit from Midwest Supplies. I plan on trying it out on a partial mash recipe in the next couple of weeks. I'm using pro-mash, and am interested in using the strike temp calculator. If anyone uses a similar setup, and has a good handle on what to plug in for thermal mass, I would appreciate the info. If not, I guess I can always low-ball my estimate, and raise the temp by adding extra 200F water until I get it right.