British Sil-Nylon Large Insertion Sack. New. Olive Green.
Genuine issue waterproof bag designed as a liner for the infantry ruck sack. Totally watertight fabric (the HH is off the scale!) but no seam-sealing so ingress through seams if submerged. Closure is via a basic tie and toggle. Could also be used as a large stash bag for kit, sleeping bag etc. Recommended.