Eureka Archimedes MT 68 plus 8 Litre Ruck Sack. Rucksacks & Day Packs. The Archimedes MT (mens) is a fully-featured, internal-frame 68 8 Litre expedition style pack for the demanding, light-weight global traveller. Added to this pack is a fully detachable daypack for use when the full pack is not required. Next to.. ...