These are actually vintage electric fan covers but they would make excellent speaker covers.
Thick, sturdy aluminum construction. The larger one with the 8 curved legs is 11 3/4 inches in diameter and should be large enough to cover a 12" guitar speaker in an existing cabinet or a custom built cabinet. The smaller one with the 5 point curved star pattern and the screen is 11" in diameter. It will easily cover a 10" speaker in an existing cabinet or a 12" speaker in a custom cabinet. These will give a unique, vintage look to your guitar amp and they are sturdy protection for your speakers. Local cash only, $15 each or $25 for both.