[Grammar] "The material is OF poor quality."

[Ackermman]

Hello everyone! I'd like to ask your opinion/knowledge on this sentence, "The material is OF poor quality." Why do we need OF in this sentence? Thanks a lot.

 

[Charlie Bernstein]

Hello everyone! I'd like to ask your opinion[STRIKE]/knowledge[/STRIKE] of this sentence: "The material is OF poor quality." Why do we need OF in this sentence? Thanks a lot.

Welcome, Ackermman!

Always tell us where you got your sentences. Did you make it up? If you read it somewhere, where? Who wrote it?