Heinrich Grenser (1764-1813) was a nephew and later also son-in-law of A.Grenser. He learned the trade from his uncle, worked with him and in 1796 took over the workshop. Like his uncle he was very well known during his life (and after) and about 150 instruments of the H.Grenser workshop are still to be found in museum collections (of which at least about 25 members of the clarinet family and about 50 bassoons). His bassoons were very famous and have been the starting point for the modern German bassoon. Likewise, the Grenser clarinets can be considered as starting point for the modern German clarinet.
The H.Grenser clarinets can be found with 5, up to 11 keys in different combinations, original or added later during the time the instruments were used. Most of these instruments are remarkable similar in design except for the number of keys. This makes these instrument very suitable to make with any number of keys from 5 to 12 or as I frequently do, make them with corps de rechange, one for 5 and one for 12 keys. This makes it possible to play music of a much wider period on basically the same instrument.