A surface speaker is essentially a speaker without its own moving surface. A normal speaker is an electromagnet that makes a surface, usually cardboard or plastic like, vibrate. A surface speaker does not have that surface and is attached directly to a surface of your choice and it makes that surface vibrate
Surface speakers are difficult to find on the internet as makes have multiples branches and some speakers are used by multiples makes and counterfeit are really frequent too, so it is hard to know what is what and it is they have so many names! Some site call them transducers, surface transducers, surface sound transducers, bone conductor transducers, audio transducer, sound exciters, exciters, audio exciters, vibration speakers, resonance speakers, resonators, shakers, structure-borne drivers, structure-borne sound converters, in-wall speaker, vibro speakers, flat panel speakers
Wowzr a gadget company makes the BOOMBOX resonance speaker. They have a V1, V2 and V3. They are small and have their own amplifier and mini-jack. They are sometime called X-Vibes Vibration Speaker too that look the same and a square one called X-Sticker that look related but do not seam to have a make. I have one that might be V1. They are really light and work ok. They have a washable sticker on them that works a lot better that I would have expected.
Adin have a selection of what they call resonance or vibration speakers.
Vibe-tribe has a few models of what they call vibration speakers that have their own amplifiers. Some have SD card readers, some are Bluetooth
Vsoundbox has one model that has a window month and is bluetooth
Mighty Dwarf has a range of what they call vibro speakers
Max Virtual sells products like hats and helmets with transducers
Elac Imago from NXT. They are sometime described as in-wall speakers. They are often sold inside a picture frame. According to Hans (thank you Hans) they sound quite well.
Adafruit has a couple. They call them Surface Transducers, and Bone Conductor Transducers when they are small. They sell amplifiers that fit with them.Dayton Audio have a large series of them. They called them sound exciters. They all need an amplifier.
Tectonic Elements has a range of what they call audio exciters
Recon has a range of flat panel speakers as they called them, that need some cases and/or amplifier.
AEC has a few modeles of vibration speakers that would need some sort of case and amplifier
MKM Display has the Soundpod audio transducer. Note that there is some bass shakers that are actually surface speakers but designed for basses mainly. Here there is a good few.
Monacor has a few what they call exciter speakers and resonators. Including the Ar-30 and Ar-50 that I have used for a few installations. I like the way they attach a lot, they have an integrated nut so you just need a bolt or your surface, or, you can use the surface mont they give you, that allows you to screw it, tape it, glue it on any surface. Not that the 30W and 50W are RMS, and they are optimistic. I worked with feedback with them, and I know that is hard work for speakers, but, they would not give as much as their specs. That says, they are waterproof, loud and sound really fine. Dayton has another 50w waterproof surface speaker. The AR from Monacor seams to be used by some other makes including PQN Audio, with the Spa TFX, Spar TBD and the Spa TM that is smaller 20W and that I did not see a Monacor version. Visation seams to have the 30W version but using 20W as specs, that would work with my own experience. The Visation is white instead of black.
Visaton has a range of what they call structure-borne drivers and structure-borne sound converters.
Feonic has a few models or what they call flat panel speakers, Surface Speaker Audio Drives, Invisible Speakers. I have been told they are the one that sound the best and definitively look more high-end, but, thinking that the surface that a surface speaker makes vibrate will change the colour of the sound so much, I don't know how much that could improve the sound. I'd love to have a listen with all sort of them to make a comparaison.