Similar in design to an Engelbert Schmid double, the Durk D4 is another example of fabulous German brass instrument design. The Durk line of horns includes an interchangeable leadpipe nib so that switching between European and American shank mouthpieces is no longer an issue. This horn #738 is fully custom made of lacquered yellow brass and a detachable bell. It also includes fully adjustable thumb and finger hook levers.
| Key: | Bb – F, easily reversible |
| Pitch: | A-440hz. up to 443hz possible |
| Bore: | 12.1mm |
| Valves: | Solid yellow brass conical valves with tapered spindles |
| Lever action: | Minibal |
| Valve caps: | Standard engraved nickel-silver |
| Thumb lever: | Three-dimensional adjustment |
| Leadpipe: | Standard gold brass with a water key and an engraved mouthpiece receiver collar |
| Water key: | Standard on the leadpipe |
| Cylindrical crooks: | Perfect cylindrical calibration |
| Slides: | The hand-lapped inner and outer slides are made of nickel-silver |
| Braces: | Made from the best solid nickel-silver rods available |
| Bell diameter: | 310mm |
| Detachable bell: | Available |
| Bell ring: | Special bronze, for long life and durability |
| Bell: | Single-seam bell tail with a fused spun bell flare. Medium-sized bell throat like that of a traditional Geyer horn |
| Possible optional finish: | Lacquered, yellow brass |
| Other options: | Adjustable Dürk pinky hook. |
