Only having the Brian Davis 2 vol. books on the Luftwaffe I cannot find these 2 insignias..

The black I know is for Construction battlions. They came in 2 sizes,,why? where on the shirt were they worn? I'd like to know some more info on these units.

Same with the yellow patch. Proper unit name?For the arm? or breast? What type unit wore these?
*Any information appreciated...,G.

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