zubzub, you can buy a Mastercool made by Raytek 12 to 1 for 50 bucks from www.ackits.com comes with case and a hand held thermometer If you can make this link work they have a article on what it can used for even checking for alignment problems http://www.rvpowersupply.comtire_saftey.htmI fixed your link - DF
I got mine several years ago at NAPA, I think about $60. Mine ios a 6:1 ratio (1" spot when 6"from gun, 2"@12". etc.). If I was doing it agaijn, I would get a 12:1. Jack