Using GridPlus SafeCards is quite similar to using standard credit cards (and the cards indeed use the same kind of PUF chip you can find in modern credit and debit cards) - if you want to transact, you have to input a PIN code. This adds another layer of security between your private keys and the world.
The cards also have a GridPlus issued authenticity certificate, without which they will not be recognized by any Lattice1 - noone can reprogram or insert a malicious card into the Lattice1 to steal your funds. Even if someone reinstalled the card's applet, they won't be able to get the certificate.
That being said, there are a few things you should keep in mind when working with your SafeCards.
You have three attempts to enter your PIN correctly. Three consecutive incorrect PIN entries and the card will brick to prevent brute force attacks (the Lattice1 will show you how many attempts you have left on the screen). Once the card is bricked, it cannot be reinitiated in any way at all - funds are gonu. Make sure to remember your PIN!
The card chip should be able to work even when slightly scratched, but of course we recommend you focus on not scratching the card's chip when you have coins stored on the card.
The chip's working temperature range is from -25°C to +85°C (-13°C to +185°F) - don't microwave your SafeCards and you should be good.