The Tropical Rucksack was introduced in 1968 as part of the M-67 equipment.The standardized Tropical Rucksack featured an OG-106 nylon pack with three outside pockets mounted on a spring steel X-frame. The outside pockets and the main compartment were provided with removable waterproof treated nylon liners, though these were often poorly coated and prone to leak.The map pocket inside the top flap did not have a liner but the underside was waterproofed. The outside pockets had strap and buckle adjustable closures and snap fasteners for quick access, whilst Velcro sealed the map pocket. It featured the “quick-release buckles” on both shoulder straps, greater carrying capacity and fewer projections to get snagged on the undergrowth.The X-frame between the ARVN Rucksack and Tropical Rucksack is a similar design but the Tropical rucksack’s one is a little bit longer. The ARVN is made by the canvas and cotton strap, the Tropical rucksack is made by Nylon with strap.
There aboves picture showing the inner pockets for Maps storage purpose on the top flap.
The contract number maked as "Year 68".
The Shoulder straps showing the "Quick release" feature, it is differnce to the ARVN and P68 Rucksack series.
The instruction of the Tropical Rucksack ( Sourced from internet)