They have a self adhesive gasket to connect them to the speaker enclosure which is already in the model. HO models require 2 of these. 15x11 ‘Sugar cube’ speaker, for DCC sound use. They are 8 ohms to work with TTS, Loksound 4, 5 and Zimo decoders.
15x11 Sugar Cube Speaker For New Hornby 9F, Fits The Built In Enclosure, TTS Etc
15x11 ESU Sugar Cube Speaker Kit For DCC Sound Decoder 8 Ohm 1 Watt, Zimo, TTS
ESU LokSound Micro V5.0 Blank Next18 With Sugar Cube Speaker 11mm x 15mm
Rail Exclusive SP15x11x12 Maxi 'Sugar Cube'Speaker