How big is the magnet and how much will it hold?

The face is 2.25 inches square. The magnet on the back is 1 inch across, so it holds a light note, photo or single sheet well but is not built for thick stacks of paper.

Will it stick to a stainless steel fridge?

Only if the door is magnetic stainless steel. Many stainless appliances use non-magnetic panels, so test with a kitchen magnet first. It sticks fine to painted steel, metal cabinets and whiteboards.

Is the design printed or a separate insert?

The design is printed on the hardboard face itself, not a loose card behind plastic. There is no pocket or sleeve to swap artwork.

Can I choose which design I get?

Yes. The magnet comes in several different designs, and the design is the option you pick. Each one is the same 2.25-inch square hardboard piece.

How does it compare with a flexible magnetic sheet?

The hardboard face stays flat and looks sharper than a thin flexible magnet, but a full-sheet magnetic back grips harder. Choose this one for looks and rigidity, a sheet magnet for holding heavier paper.

Will the corners or edges wear over time?

Hardboard is pressed wood fiber, so a hard knock or a wet wipe along the edge can raise or chip it. Keep it dry and it holds up well in normal kitchen use.