Sturm and Handels GMBH Jacket

This looks like a mechanics jacket, but I have no idea. The tag says "Sturm
Handel's GMBH
GR. 50 (M)
Made in Germany".

There's an inner pocket on the left, and there's a stamp on it that says,
" NVA 1958" (there is something else stamped below that but I can't make it out )

(It looks like there might be a belt missing? A lot of snaps on the bottom).

Any help with this would be very appreciated! I've been holding on to these military items for years, always hoping someone could teach me what they are.