These timpani, dating from about 1920 are suitable for 20th Century repertoire and I use them in large symphony orchestras.
I have an unusual set that are the English way round in these sizes 21″ (hand crank), 24″ (‘D’ drum), 26″ (‘D’ drum), 27″ (‘A’ drum), 29″ (‘A’ drum) and 31″ (hand crank).