If your product has 3M logos on the liner but is selling for substantially less money, most likely you are being sold 846 Series (Uncleared) film.  Also known as surface protection film.

846 Series UNCLEARED film has NO WARRANTY from 3M for exterior use.  Please see Page 7 in the Warranty section of the 3M Application Guide for Professional Applicators (PDF) for details.  UNCLEARED film is specifically excluded in the 3M Warranty.

Often referred to as 8 mil, this film is like 848 Series, but has no UV clear coat protection and is not an exterior product.  Naturally it costs much less.  However it is only intended for automotive, aerospace and industrial use where exposure to the sun's damaging ultraviolet light (UV) is not an issue.

This product is used primarily because it is less expensive.  Some on-line vendors and auction sites pass off 846 Series Uncleared film as 848 Series.  Customers compare prices, and find that vendor less expensive.  Such misrepresentations do no service to the integrity of the PPF industry or the 3M brand name when customers who think they bought 848 Series ultimately experience product failures like cracking or yellowing.

The best way to avoid this is to deal with a 3M Certified Installer.  Simply go to mmm.com/paintprotectionfilm and follow the 'Where to buy' link.  

Don't be shy about asking your new car dealer, installer or kit vendor what Series film is being used.  It will be on the box of bulk film along with the manufacturing date and lot number, and also inside the core of the roll.

If you are getting professional installation, ask for your 3M warranty documentation.

FAQ - Why is NoChip™ more expensive?