5.11 Tactical Rush Tier System5. 11 Tactical Rush Tier System Versatile and sure to prove invaluable to meeting your tactical and long distance travel needs, the RUSH Tier System is a 4 piece strap system designed by 5. 11 Tactical. It attaches 5. 11s RUSH MOAB packs to the RUSH series bags. Once installed, it allows quick and easy attachment and detachment of MOAB packs from RUSH main pack. Its the ideal system for quick connect and disconnect capabilities in a modular storage