This slick little piece of steel is a magnetic-mount tape holder.
It can hold smaller-diameter tapes (like electrical) on the inner fins, and larger-diameter (duct, packing, blue) tapes on the outer fins.
The gap in the fins allows it to accommodate some dispensers.
It’s made for tape rolls that are up to 2″ wide.
It’s made by Japanese housewares brand Yamazaki Home and runs $20.