Apparently there's a mistake on the product page.

I forwarded the error. If you bought this item by mistake, thinking it supports Bluetooth, please contact customer support so you can return the item. As far as i know, there is no model of this mouse that supports (real) Bluetooth (without the included Dongle).

PS: You may also report wrong entries yourself on the Product page -> Specifiactions -> Show more -> Scroll down -> Report incorrect data and adjust the corresponding entry directly