New to this site, thanks for admission. So, I bought these two used a week apart and I have some observations. The one on the left is a BA115 and the one on the right is a BA210. They sound very similar even though the power output is much greater for the 210, I don't notice it much. Perhaps at peak volume levels I would. The 210 has a top mounted internal cooling fan and an external speaker jack on the rear, neither of which the 115 has. There is a high frequency (HF) mute button on the front panel of each, but I don't notice any difference in sound for either amp when I engage it. I'm wondering if the piezo driver is not working on both! Anyway I plan to use the 115 for rehearsals and small gigs and the 210 if I play a larger venue or outdoors. I think I did pretty good at $350 for both.