8 Ohm 20x40mm speaker which fits into most locomotives with ease. These are often seen as the industry standard so they fit into almost any loco. they can be used on their own or to get the best out of them they can be fitted into an enclosure and sealed. Ideal for Hornby TTS decoders as well as Loksound 4 and Zimo. They have large soldering pads which makes connecting them to your decoder simple.
If you fancy something which sounds a bit more powerful please take a look at my other 'upgrade' speakers in my ebay shop. I also offer a fitting service for anyone who needs it.