I bought these to build a three-octave pentatonic glockenspiel my self.
The sound is quite dull and meh because these are just sheet steel, not as nice as the bronze keys I have on a fine glockenspiel I bought in a special store elsewhere. They're half round bronze and these are flat steel. I might try and remove the paint with some chemical from these (sanding could affect the tuning at worst).
That could make the sound brighter. I hope not too harsh though.
The colour is also quite ugly to my taste. If you find these too bright and ugly you could just use thick paint on them.
I wouldn't recommend these as spares for any real instrument but for a DIY-project they're cheap.
Overall; theyre very very OK :)