Text copied from TM-E 30-451, March 1945 :

"3 Kilogram (6.6 Pounds) Slab (Geballte ladung 3 Kg.).
(1). Description: This slab, in a zinc container with a carrying handle at one end, has either three or five sockets for standard caps and holders or igniters. The container is pressure-resisting and the slab may be used under any depth of water. This slab is often used with igniters for improvised mines. It is marked 3Kg. on the side.

(2) Characteristics: Weight: 6.6 pounds, Height: 7.9 inches, Width: .. inches, Thickness: 3 inches.

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