Okay... It does reduce vibrations, I won't say it doesn't... But not completely... I would say it reduces about 60-70%... It's a must, I would say, for today's air conditioners that vary the compressor speed and make the walls shake when metal touches metal at the base and the compressor changes speeds...
In conventional ones with fixed speed, the noise wasn't as intense except when the compressor stopped, and you thought the wall would fall... Generally, guys, for €10 including shipping, don't think about it... Get them or ask the technician to install them during the initial setup... They charge €10 again... That's what they asked me, and I didn't get them, but I regretted it later and ended up buying them from here...
In the other house, because the space is different where I have it, in the kitchen not in a room, the same model doesn't make as much noise; maybe the wall makes a difference, I don't know, and I have it there without rubber pads, but I'll see... Maybe I'll put them there too...
Unless you have a very quiet and well-secured machine and it’s not necessary....
In my house, out of the 4 I have from before, 2 conventional and 2 inverter, I only needed to install them in the newest one... That's it...