Upgrade your standard Hornby TTS speaker with one of these fantastic iPhone speakers, this is pre wired and insulated and is ready to use, simply disconnect the existing round or rectangular speakers and join the wires.
This speaker is small enough to fit in almost any model, it measures just 30x20x4mm, there's also a slightly larger version available in my other items which is 35mm long. (see second photo where they are shown side by side)
If you have any questions please don't hesitate to ask.