I think nowhere other you can find such black corners, except in the Thomann Store and there is also no second brand, that provides them here.
-Very cheap, you always need 8 pieces, so you get the quantity discount
-Powder coatet with black lacquer/powder
-applicable to Amp or Box (belongs to the type but in most cases, its possible)
-fast applicated, two screws and the work is done
-Maybe I have got a bad charge but I was not very happy with my corners:
They were stacked together while they was not fully dryed.
Therefore some parts are thick (like sand under the painting) and not good coated on 50% of the corners.
The cheap price makes it gainless to send them back so i decided to put them on corner on the floor of the Box.