Help ID this Kriegsmarine badge

[BenVK]

Hi guys, I've been offered this badge as a refund for $13 worth of postage that I shouldn't have paid on a cap I recently bought.

Should I get the cash or keep the badge?

[Besian B.]

Greetings Ben,

That's a KM specialist's insignia, and it's missing the cloth backing along with the small metal backplate. I think it is probably of the signal personnel due to the lightning bolts, but I stand to be corrected. However, $13 would be a rough estimate of such a piece in that condition.

[BenVK]

Not a rare badge then by any means?

[J.von Canon]

only a piece of a badge...

Not a rare badge then by any means?

No.Common Kriegsmarine Signals "trade" badge-but only a piece of it.
As mentioned-the heavy cloth,metal plate backing is missing...