Walmart samples are the best ones to get, because they usually come within 1-2 weeks. I have received several samples from Walmart very soon after sending for them.

Walmart is giving away a free sample of Listerine Whitening Strips

Enjoy a noticeably whiter smile in just two weeks — and it’s refreshingly easy. LISTERINE WHITENING® Quick Dissolving Strips are thin, virtually clear strips that start to work as soon as they are applied to your teeth. The strips simply dissolve as they work to whiten your smile, so there is no messy gel and nothing to remove.

For more information about the product check out the walmart free samples page