Whether you’re packing your bags to fly to Europe, Grandma’s, Disneyland or some other exciting destination this summer, it pays to have the right luggage that stands up to the stress of the trip.

If you’re purchasing luggage for your summer travels, focus first on durability, the number one determinant of overall satisfaction with a piece of luggage for 57 percent of respondents in a Consumer Reports survey. Understanding how UL tests luggage can help you make a better buying decision.

Pay Attention to Wheels

Arguably, wheels might be the biggest innovation in modern luggage, freeing travelers from the need to carry heavy suitcases. Wheels, though, prove to be vulnerable to damage, as they endure much abuse going over bumpy sidewalks, rolling off/up curbs, moving across debris-strewn parking lots, etc.

According to an article for Inside UL, to simulate these real-world conditions during luggage tests, UL uses a giant rubber walkway that includes a one-quarter inch bump every 15 feet. Tested suitcases are loaded with weights as if packed with clothing and other items, and then hooked up to cables and cords that automatically roll the bag down the walkway. Several hours later, UL technicians examine the wheels for wear, cracks and breaks to see how the wheels held up.

Although you won’t be able to duplicate this rigorous test, wheels are an area that you’ll want to examine carefully when considering luggage. Look for wheels that roll smoothly, advises Consumer Reports, and pick up the suitcase and jiggle the wheels to make sure they feel firmly attached.

Test Handles

UL spends considerable time testing suitcase handles, using a simulated drop and jerk test on both the top and side handles. First, a UL technician adds the right amount of weight to the bag to simulate real-world conditions, then anchors the suitcase to a machine and properly balances it. Once the test begins, the machine drops the suitcase 4.5 inches, then pulls it back up – and repeats this 500 times per luggage handle.

Later, the technician examines the suitcases, checking for rips and other signs of damage, particularly around the handle seams. The technician also tests whether the handle still works well.

You won’t be able to conduct this drop test in the store either, but you’ll want to look closely at luggage handles. The handle should have little to no wiggling or rattling as you pull the bag around the store, Consumer Reports advises. Also, pull the handle out and retract it several times to check for smooth, easy movement.

Examine Zippers

Zippers are another potentially weak area in luggage. Try the zipper to make sure it runs smoothly and feels strong and durable. Next, examine the stitching around the zipper to make sure it’s reinforced. Also, look for a big zipper with big zipper tabs, as these are stronger and more durable.

With these tips, you can choose more durable luggage, which will help make your travels easier and more relaxing.