Thank you for viewing. This is a Giddings & Jackson FH-2.75 horn mouthpiece. Inner Diameter: 17.5mm Throat Diameter: 4.699mm Depth: 25.273mm Unlike typical mouthpieces, this one is made of stainless steel. I purchased it used and used it several times, but I'm selling it now as I no longer use it. I will clean it before shipping, but please understand that it is a used item before purchasing.