If you bought a new phone in the past few years, you may have spent a thousand dollars or more for ant Apple or a Samsung model. Considering how much they cost and how much wear and tear they take, it makes sense to protect them with a good case. Consumer Reports explains what to look for to protect your pricey device.

Consumer Reports says you can get a good case for under $30. Make sure it has these features.

A raised edge around the front to protect the front screen and another around the camera housing on the back. You want the case to be tight-fitting with padding on the edges.

That tight fit will keep the case in place should you drop your phone. And because phone makers often change their phone designs ever so slightly, you’ll likely need a new case every time you get a new phone.

Even better, choose a phone that scores a 4 or 5 in CR’s intense durability tests, which include a drop test performed with phones without cases.

The phone is dropped 50 times, then checked for any scratches or damage. And then it’s dropped it another 50 times.

The best phones make it out of the tumbler with just a few scuffs or scratches.

More tips for choosing a phone case:

Buyer beware: There are plenty of knock offs out there, so know who you’re buying from.

Be wary of online reviews. Many of them don’t tell you how a case withstands the test of time.

And finally, look for a warranty. For instance, OtterBox and Speck offer good options.

You can’t deny that it’s an aesthetic purchase, too. You might find a case that’s really well designed and also sparks some joy in you every day, and that’s the kind you should go for.

Because phones are expensive to buy—and expensive to fix—if you’re someone who’s really tough on yours, you may want to consider investing in phone insurance. You can get it through Apple, Samsung, or most other phone carriers.