DJ type - Low temperature. Suitable for -18- -31'C cold room, keeping for such as fresh meat, fish and fast frozen DD type - Medium temperature. Suitable for -2 ~ -18'C cold room, keeping for such as meat, aqutic prodcut. DL type - High temperature. Suitable for 12 ~ -2'C cold room, keeping for such as vegetable, fruit, eggs. SGS, CCC, CE, ISO.