The 31136 is an 8 GB flash drive with the Campbell Scientific logo on it. It is useful for transfering files, such as program files, for users who do not have a CD/DVD drive but do have a USB port. One 31136 ships out with each PWENC12/14, PWENC14/16, and PWENC16/18 ordered, and it can be found in the desiccant/document holder bag inside the enclosure. When the 31136 is shipped out with a pre-wired system, it contains an electronic copy of the system's programs and wiring diagram.