I renovated a new office space with large steel sash windows. We were getting too much solar gain, so I had some valences made to cut down glare. I used these magnets to attach the fabric valances to the smaller valances, part of solar roller shades that are installed. Clean and worked like a charm.

The title says it all

Those magnets are very fragile.
Already 2 of them broke into pieces

Good strong magnets with competitive pricing.