Equipment covered by this specification is intended for use in testing equipment and systems in the worldwide natural and controlled environments in which Military equipment is operated (on a continuous or intermittent basis for extended periods of time), either stored or transported, or both, including utilization in all types of moving Military and commercial vehicles (land, sea, and air). The extent of an equipment's penetration (levels of use) into the Military environment is limited by its classification (type, class, style, and color, as specified in 1.2). Selection of the correct class is essential to ensure procurement of the desired equipment. Where needs supersede requirements, this specification can be referenced in part. Where environmental eeds overlap specific classes or styles, the lowest appropriate class or style (lowest environmental resistance) will form the basic requirements, and the additional specific requirements will be selected from the higher classes. The inclusion of batteries may alter the environmental resistance of equipment designed to operate from either internal or external power sources or both.