Initially, the Thompson submachine gun appeared in 1919 and, since then, the weapon has undergone numerous revisions. One of the things that sets the Thompson apart from other submachine guns is that while most are made to be as inexpensive as possible, the Thompson was designed to be a truly high-quality weapon. That said, it had a relatively short effective range, was expensive to manufacture, and weighted more than others, such as the Sten Gun. Fortunately the Thompson used a larger, more powerful round, the 0.45 ACP, as opposed to other submachine guns used during WWII.
M1 Thompson on Wikipedia