With the introduction of the 4-Sight, Think Tank Photo has created an entire new category of lightweight rolling camera bags.Think Tank Photo set out to design a more ergonomic roller to reduce fatigue and strain on traveling photographers. The result, the first four wheel roller designed specifically for photographers. It meets International airline carry-on standards, (always check your airline for current size restrictions). Weight has been dramatically reduced through innovative bag design and a strict focus on features that photographers identify as most beneficial. A lockable zipper provides security.