This new version of the D4 is very different from the earlier version. It's a completely new design which has been given the same name as the discontinued model. In fact, it bears more resemblance to the D3, in that the engine components are the same.
The boiler is heated using a pair of beeswax candles. It is mounted on a decorative stand, supported over the candles by two pillars on one side and the engine frame on the other. The boiler is 45mm diameter x 100mm long. It has a standard Wilesco circular sight glass on one end. It has a steam feed pipe, safety valve and whistle on the top.
There is no steam dome, regulator or lubricator. The steam pipe is fed directly to the top of the engine port face. The engine is a single acting oscillating cylinder; identical to that on the D3. It is 6mm bore x 16mm stroke.
The whole sits on a wooden base, which locates the two candles under the boiler. The boiler and engine assembly lifts off to gain easy access to the candles.
Performance is rather disappointing using the candles so I use a small meths burner instead for running.