Double walled and double door. Temperature controlled by thermostat with dial type thermometer , Forced air blower.Chamber Size Tray Inner S.S. Inner M.S430x840x650 8 Tray 46200.00 42000.00430x840x910 12 Tray 56600.00 50400.00910"x840x910 24 Tray 81800.00 68000.00 There are Many Sizes OPTIONAL:1. TImer0-24 hours. 2800.002. Digital Temp. Indicator cum controller 6600.003. Tray 16"x32"x1/4" Size AL 800.004. Tray 16"x32"x1/4" Size SS 1500.00