The cassettes are absolutely great for the money and they are sound-neutral ... as opposed to Sony / TDK cassette are not artificially raised here the bass (though they have characterized a dynamic drop of ca.2-3dB). With my Nakamichi 480/680 I managed class recordings here. The belt has a low noise and a good mechanics. Who wants to have a good case and do not want to buy expensive material used is well served here. The only pity is that the C-90 are no longer available ... :(
PS: Each cassette has in me ca.64min term ... tested on 4 tapes Denon 710, Yamaha KX-650RS; Nakamichi 480/680 !!!