Oh, bummer...
First message:

Thank you so much for your help!

we will report this to the product team and they may consider about list the magnetic disc separately. But we are not very sure about their opinion.

Besides, the magnetic disc in SKU 9641287 (the kit) can be unscrewed from the tank, so you may use it with other tank

thank you



Second:

We are sorry to inform that the supplier doesn't sell that magnetic disc separately.

really sorry for this. we can't help in this case

thank you