There a few rules for installing a card into a device.
The device will have an opening for the card that should be identified.
In the photo on the left is my phone; the lid shows the shape of the card and spells out microSD.
In the Center is the opening for a Mini Mp3 player it is identified as TF-Card (old name for SD) and shows the shape of the card.
On the right is a micro SD card note the shape matches the markings on the devices.
Please note that the shape marker on the device may not show you what direction the card should be in when it goes into the device.
For this MP3 player the shape is opposite of the way card should be installed.
Never force a card into a device!!!!
The card should go in smoothly. If it hangs up try flipping it over.
