Filter the preorder products | WordPress.org

Hello,

I have filters on a frontend sidebar where I can filter the products by stock status, categories… and I’d like to add a filter for preorder products.

The best would be to filter them with stock status but I don’t know if it’s possible.

I use Filter Everything Pro and I can add a filter by custom Field, can someone tell me what is the name of the custom field for the preorder products please?

Or if there is another way to filter them?

Thank you!