GMNA C141 PDF

This standard for Metric Oval 90° Countersunk Trim Head Type 1A Cross Recess Machine Screws conforms in all essentials, except head proportions, with the American National Standard covering metric machine screws. Basically, the smaller head proportions of the trim heads were derived by applying to the respective screw diameters the 1976 standard oval head diameters applicable to the next smaller screw size, and specifying a rounded edge. It should be noted that, for the most part, the Type 1A cross recess configuration will serve to identify these screws as being metric.