The MK 41 VLS is the international launcher of choice for surface ships capable of launching anti-air, anti-submarine, surface-to-surface and strike missiles. The Mk 41 is capable of firing the following missiles: RIM-66 Standard, RIM-67 Standard, RIM-161 Standard Missile 3, RIM-174 Standard ERAM, Tomahawk, RUM-139 VL-ASROC, RIM-7 Sea Sparrow, and RIM-162 ESSM. The missiles are pre-loaded into “canisters”, which are then loaded into the individual “cells” of the launcher. The ESSM is loaded in a quad-pack with 4 missiles in one Mk 25 canister. Launcher cells are fitted to ships in 8 cell (2 rows of 4) modules that share a common uptake hatch (exhaust system) sited between the two rows. Mk 41 VLS adopts modular design concept, which result in different versions that vary in size and weight due to different “canisters” in various modules. The height (missile length) of the launcher comes in three sizes: 209 inches (5.3 m) for the self-defense version, 266 inches (6.8 m) for the tactical version, and 303 inches (7.7 m) for the strike version. The empty weight for an 8-cell module is 26,800 pounds for the self-defense version, 29,800 pounds for the tactical version, and 32,000 pounds for the strike version. Originally, one module would consist of five cells and a collapsible crane for assisting with replenishment at sea, but replenishment of large missiles at sea was later seen as impractical and dangerous, and modules with the cranes fell out of use.