Horst Grünert specialised solely in builiding and restoring elli and double basses and their baroque predecessors.
Clos and permanent relations to musicians developed and "Grünert-Instruments" are played in distinguished orchestras around the world.

For instance:

- Vienna Philharmonic Orchestra
- Vienna State Opera House
- Vienna Symphonic Orchestra
- Bavarian State Opera House
- Pittsburgh Symphony Orchestra
- Opera National de La Monnaie at Brussels
- Teatro Real at Madrid
- Nederlands Philharmonisch Orkest, Amsterdam

Back view of a Grünert-Kontrabasses