tessitura?

ASAIK tessitura is the range of sound (the pitch in a general way) of an instrument -- usually referred to in vocal -- as in, "the tessitura of the soprano...".
For tubes, I dunno. What's the tessitura of a tube? A mezzosporano tube? A baritone tube?
He probably means the following: please buy from me. All my tubes are outstanding (as everyone else's) but I know and use the word tessitura that others don't. So choose me.

Hi, I'm Italian. The word "tessitura", strictly translating, means texture, but I imagine in that case it is used to describe a liquid, organic, smooth sound. The type of sound usually referred to a tube device. So... it means nothing.

I've heard the word used idiomatically to refer to a range of pitches. As in cellos,trombones,tenor human voices,and bassoons share the same tessitura.