WW2 German 2.8 cm sPzB 41

[Danilov]

Hi everybody.
This German cartridge was given to me by my digging friends for a long time. Now I have identified it as a cartridge of the s.PzB.41 heavy anti-tank rifle.
There is a military acceptance stamp with an eagle and a year of manufacture.
I haven't come across such before.
I want to know how rare this item is, are there many of them in the collections?
Sincerely.