Outer made of Mild Steel and inside made of stainless steel 304 qlty. Insulation between the two walls are done by PUF insulation. Temperature from ambient to - 40 Deg.0 is be controlled by microprossed digital temperature controller. It has low & high temperature cut in the range of 1 Deig.c fitted with hermetic compressoer with CFC free refrigeration system. It is supplied with automatic voltage stabilizer & chart recorder.