Review on Metal Magnet Sliding Webcam Cover Slider – Protects Privacy for Laptops MacBook Pro HP iMac iPhone Cellphone – Reliable Adhesive – Pack of 6 (3 Black + 3 Silver) by Dan West

I don't know why but I expected them to be much larger. Look at their pictures installed on a laptop and you will see how small they really are. I also thought the round part slides into the rail, but it's magnetic. You have to be careful opening and closing them so the round part doesn't fall out, but other than that they're easy to use. I use them on my laptops (Macbook Pros) and they are fine. They don't protrude far enough that the laptop doesn't fully close. I'm not sure if the small round part will remain if you use it on a mobile phone. I'm sure I'll lose the round part when I put the phone in my pocket or take it out. Otherwise, they're fine on a laptop with the lid closed in transit. They're five stars for what I bought them for, but I think I'd rate them pretty low if I were to use them on a mobile phone and lose part of the drive, which I sure would since it's not there is trace.