The Czech Backpack is a 24 slot backpack capable of holding 4 secondary weapons or 2 primary weapons or 1 primary and two secondary weapons. It's tied as the largest backpack with the Backpack (coyote). As of 220.127.116.11 it can only be found in medium/high value military installations, such as the NWAF barracks. It is taller and less wide than the Backpack (coyote), but it is also thicker, resulting in overall more bulkiness than the Coyote Backpack.
However, this is balanced by the fact that the Czech Backpack features a woodland camouflage pattern, identical to the one used on the Czech Vest Pouch, allowing it to blend in with the environment much more easily than for example the ALICE Pack or the Coyote Backpack, since over half of the terrain of Chernarus is thick woodlands.