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

"1-Kilogram (2.2pounds) Slab (Sprengbüchse 24).
(1) description. This slab may be made either from TNT or picric acid, in a pressure-resisting zinc container which permits it to be used at ant depth of water. There are three sockets for standard caps and holders, or igniters-one on each face of the slab excluding the base. Each socket is covered with a paper disc marked Sprengbüchse 24 and either Fp02 (TNT) or Grf88 (picric acid).

(2) Characteristics: Weight: 2.2pounds, Length: 7.9inches, Width: 2.9inches, Thickness: 2.2inches".

On the right photo you see a thirt version that I hadn't seen before.
Not made of zinc, this 1kilo charge was made of sheet steel, folded rims.
It also has 3 fuze wells like the charges shown above but positioned differently. Green paint.
Makers mark CMP 1943. The paper label on one of the fuze wells says "Sprengbüchse 28B".


Below :
A training model had a similar shape, made of thick steel and a removable lid.
The cover exists in two types (different closure), the body has the same fuze wells as the live one.