August Grenser (1720-1807) was a well known instrument-maker during his lifetime. He worked in Dresden from 1744 where he got the predicate 'Hof-Musikalischer instrumentmacher' 1753. He made all kinds of instruments and more than 60 of them are preserved. Among them at least 5 clarinets, 5 basset-horns and a bass clarinet. Leopold Mozart is known to have ordered instruments from him.
The B-flat clarinet I copy (possession E. Hoeprich) is an example of a very early classical clarinet. It started its life as a 4 keyed instrument with double holes for finger 3 and 7. Later, probably early in its life, it got key number 5 F#/C# added. It is a beautiful instrument, very well suited for most music before 1800. I make my copys with the 5th key and mostly without the double hole for 7.
I have at the moment a copy of a very similar clarinet in A (A.Grenser, National Music Museum Vermillion) dated 1785 in preparation.