We believe we are the world's leading provider of portable storage solutions, and are committed to providing our customers with superior service and access to a high-quality and diverse fleet. We are also a leading provider of specialty containment solutions in the United States ("U.S."). Our mission is to uphold our leadership positions in portable storage solutions to customers throughout North America and the United Kingdom ("U.K.") and become the provider of choice for specialty containment products in the U.S.
Mobile Mini, founded in 1983, focuses on renting rather than selling our units, with rental revenues representing approximately 94% of our total revenues for the year ended December 31, 2018. We believe this strategy provides us with predictable, recurring revenue. Additionally, our assets have long useful lives, low maintenance and generally maintain their value throughout their useful lives. We also sell new and used units and provide delivery, installation and other ancillary products and value-added services.
Our business is comprised primarily of two product categories: