The ESU 50344 is a repackaged Tang Band T0-2008S. It measures 9mmH x 24mmW x 55mmL (without the mounting tabs, which may be trimmed off). It is a 1W, 4Ω speaker and features a passive-radiator to extend the low-frequencies. I do find the upper-mid and high-frequencies are a bit lacking in these, but otherwise these are great speakers if you have the available room and work well paired with a Boiler-Barker or another of my speakers to extend the overall frequency-response. Some steam sounds can cause the speaker to crackle or distort at higher volumes.
Since these are 4Ω speakers, you will need to wire them in series when paired with another speaker.