Casio Previa px-160

I have a Casio Previa px-160 i need to replace the hammer weight.
It is key c32 but i’m not sure which option to choose on the website.
can anyone help?

The key to replace should have a designated code on it somewhere, like “B1, B2 or W1, W2 etc.”

it was the counterweight But once i got it out an played with it. It had come unlocked once locked it was good to go .