The RIM-66 Standard MR (SM-1MR/SM-2MR) is a medium range surface-to-air missile (SAM) originally developed for the United States Navy (USN). The SM-1 was developed as a replacement for the RIM-2 Terrier and RIM-24 Tartar that were deployed in the 1950s on a variety of USN ships. The RIM-67 Standard (SM-1ER/SM-2ER), is an extended range version of this missile with a booster stage. The Standard can also be used as an anti-ship missile.