Mark 21 fuze test (IMAGE) DOE/Sandia National Laboratories Caption Sandia National Laboratories tests a prototype of the Mark 21 fuze to ensure it meets requirements and specifications. The first production unit of the fuze, which will be installed in a weapons system, was accepted in March. Credit Photo courtesy of Sandia National Laboratories Usage Restrictions Photo can be used with story about Mark 21 fuze first production unit License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.