GMNA C121 PDF

This standard for Metric Oval 90° Countersunk Head Type 1A Cross Recess Machine Screws conforms in all essentials with the American National Standard covering metric machine screws. It should be noted that, for most screw sizes, the head diameters specified herein differ from those documented in prior issues. Therefore, it is recommended that any countersink provisions in existing designs based on former metric oval head screw standards be reviewed and adjusted accordingly. In general, screws made in conformance with this standard are considered to be functionally interchangeable with parts produced to the latest IS0 Standard for recessed raised countersunk head screws. Also, for the most part, the Type 1A cross recess configuration will serve to identify these screws as being metric.