Towards the end of 2023 I bought myself a Yamaha P45 portable plastic piano, and the usual accessories, including a folding piano bench. It's okay, but eventually I'll buy a proper piano bench for home, and just use this to take to gigs. It has its problems, and could do with some redesigning.
There's thick cushioned top with a vinyl cover. That makes it easy to keep clean, but does mean it's going to make you sweat in hot weather (Australia is a hot country). And it makes amusing whooshing noises as you sit down and get up. Some large vent holes under the seat might have been a good idea.
It also has various creaks and rattles from the legs, so not the best choice for use in a recording studio. I found it making loud annoying noises at the worst moments while making recordings.
The height adjustment range goes from too-low to too-high, and seems to have enough steps in-between, so should suit most needs. We use one of these benches with a piano on ridiculously large wheels, necessitating a tall bench to be able to play properly. And I added a couple of extra positioning holes, on mine, to go even lower to suit an awkward keyboard playing situation I had to contend with for a while.
The height adjustment is done by pulling in a couple of plungers at the top of the legs, and repositioning where the legs lock into some holes in rails under the bottom of the seat. They're not a firm fit, so that adds to the noise of the seat. The knobs screw in, and while they can be tightened up, they have to be slightly loose to be able to adjust (or fold-up) the seat, and this can lead to them eventually falling out (as happened to someone else with the same seat, and they lost the knob—they use a M6 thread if you need to replace any). The knobs also stick out a bit too far, and the plungers often get wedged while you're trying to adjust the seat, because they get pushed into the side of their pipe instead of sliding along it. Those knobs have sharp edges, and so did something else near them. Two of us have ended up with metal splinters in our fingers after handling the seat, on a couple of occasions. I had to play at a gig after getting one stuck very painfully in the tip of my finger.
I put some markers on the rails so I could quickly find the right holes for my preferred bench height in the dark (as can be seen in the above photo). Trying to line things up on the floor in low lighting, when virtually all the parts are black was a bit difficult. And it's tedious trying one position, turning the seat over to see if it's the right one, then turning it back over to make another adjustment. Rinse, lather, repeat…
It's a bit of a rat-trap to carry while folded, there's nothing to stop the legs flapping about, and it bites you if you're not careful.
The rubber feet come off too easily, so I've glued mine on.
The feet stick out wider than the bench, and I've stepped awkwardly on them many a time when standing up and stepping around the bench.