Any idea how strong they are?

At work, we have semi-opaque glass in our doors. It's not clear, but people can see if you're if you're in your office and it's clear enough that I've asked for some sort of blinds when I come back from maternity leave for pumping privacy.

But our building was recently renovated, so they're very hesitant to do anything permanent (and they want all offices in the building to match). So my bosses have suggested magnetic blinds.

The window is the full length of the door, so I don't imagine the blinds are very light. Has anyone used magnetic blinds? Have they stayed put well?