Most suitcases manufactured today stand upright and feature a recessed handle of some sort.  The handle is designed so that when being transported, or not in use, it recesses into a aperture in the case, and either locks in place, or is covered by a zippered flap, or both.

These wheels are of similar construction and design to those found on "rollerblade" or in-line skates.  The wheels are usually placed at or near the corners of the case, maximizing stability.   Due to their low profile, they are extremely difficult for handlers to damage, or break.  At the center of the wheels is a ring containing ball bearings, it sits between the wheel, and the pin, which the wheel spins on.  The ball bearing wheel absorbs all the friction created when the suitcase is pulled.

Skywheels are a registered trademark of Skyway Luggage.  They are a wheel similar to the above mentioned rollerblade wheel, but the wheel itself is made of vulcanized rubber, more dense than the tire on your car, and almost as dense as a hockey puck.  They are almost always placed at the corners, and feature built in runners for sliding up and down stairs.

Offered on many cases, these corner protectors offer an extra layer of abrasion protection from the corners of your suitcase.  They are featured on many suitcase, but are most valuable on any piece that you will check in, as opposed to a carry-on which you will handle, and thus should not normally be exposed to rough, or abusive, handling.

ValleyZip is a unique method of construction that places the otherwise vulnerable main compartment zipper into a protected channel or "valley".  This zipper valley is recessed in from the edges of the bag, far away from abrasions.  Zipper failure due to mishandling abrasion or impact is virtually eliminated.  Travelpro's exclusive ValleyZip construction is sewn with continuous filament nylon thread for stronger and longest life.

A large selection of luggage is made of Nylon, which is produced under a variety of names; Ballistic nylon, Denier, and a variety of other names.  While there is some difference between the assorted nylons do not put too much weight on their rating (i.e. 1800, 2500 etc).  A much larger factor in durability is how well the case is actually assembled.   The number beside the name of the material refers to the number of threads per inch.  Therefore, if the luggage is made of 1800 denier, that means there are 1800 threads per inch, usually 900 going one way and 900 the other.

Hardshell Luggage is often constructed of polypropylene, a molded plastic material which is extremely resistant to denting, bruising, bending and crushing.  In fact, you should be able to stand and jump up and down on an empty polypropylene case, without fear of damaging it.  This is something you should never do to an empty softshell suitcase.

ABS is a lightweight plastic used in certain softshell luggages.  While it has a molded form, similar to a polypropylene case, it should never be traveled with empty, as it is easier to damage.  It offers more natural protection than a softsided case, but not as much as a polypropylene case.