An affordable inventory upgrade, Standoff Land Attack Missile Expanded Response (SLAM ER) incorporates a number of improvements to the baseline SLAM, a derivative of the Harpoon anti-ship missile. These retrofit upgrades include planar wings to improve range and aerodynamic performance, an improved warhead to increase penetration and lethality against hardened targets, and software improvements that make it easier for the control aircraft to designate track on the target aimpoint.

Designed for deployment from carrier-based and land-based aircraft, SLAM ER can be adapted for ship launch. SLAM ER can be launched from safe standoff ranges of more than 150 nautical miles.