Reebok Jet 300 Treadmill – 538/6406

Year 300 (CCC) was a leap year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Constantius and Valerius (or, less frequently, year 1053 Ab urbe condita). The denomination 300 for this year has been used since the early Middle Ages / Medieval period, when the Latin language term / abbreviation "Anno Domini" ("In the year of Our Lord") for the calendar era became the prevalent universal / worldwide method for naming and numbering years. First beginning in Europe at the end of the Roman Empire (after the split of the Western Roman Empire and Eastern Roman Empire (later Byzantine Empire) in the early Middle Ages / Medieval period.

Then the Christian-oriented dating system then spreading west across the Atlantic Ocean with the Western European explorers and religious faith to the continents of the Americas of the Western Hemisphere, then through the simultaneous movement of the various Christian churches, and Europeans along sea trading routes with the military / political / economic / social influences of Colonialism / Imperialism spread worldwide to Africa, Asia and Australia / Oceania.

Year 538 (DXXXVIII) was a common year starting on Friday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Iohannes without colleague (or, less frequently, year 1291 Ab urbe condita). The denomination 538 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.

Reebok International Limited () is an American footwear and clothing brand that is a part of Authentic Brands Group. It was established in England in 1958 as a companion company to J.W. Foster and Sons, a sporting goods company which had been founded in 1895 in Bolton, Lancashire. From 1958 until 1986, the brand featured the flag of the United Kingdom in its logo to signify the origins of the company. It was bought by German sporting goods company Adidas in 2005, then sold to the United States–based Authentic Brands Group in 2021. The company's global headquarters are located in Boston, Massachusetts, in the Seaport District.

A treadmill is a device generally used for walking, running, or climbing while staying in the same place. Treadmills were introduced before the development of powered machines to harness the power of animals or humans to do work, often a type of mill operated by a person or animal treading the steps of a treadwheel to grind grain. In later times, treadmills were used as punishment devices for people sentenced to hard labour in prisons. The terms treadmill and treadwheel were used interchangeably for the power and punishment mechanisms.

More recently, treadmills have instead been used as exercise machines for running or walking in one place. Rather than the user powering a mill, the device provides a moving platform with a wide conveyor belt driven by an electric motor or a flywheel. The belt moves to the rear, requiring the user to walk or run at a speed matching the belt. The rate at which the belt moves is the rate of walking or running. Thus, the speed of running may be controlled and measured. The more expensive, heavy-duty versions are motor-driven (usually by an electric motor). The simpler, lighter, and less expensive versions passively resist the motion, moving only when walkers push the belt with their feet. The latter are known as manual treadmills.

Treadmills continue to be the biggest-selling exercise equipment category by a large margin. As a result, the treadmill industry has hundreds of manufacturers throughout the world.