All the classic details of the time honored original are reproduced in today's semi-auto Thompson. The frame and receiver are machined from aluminum and weight is only 9.5 lbs, compared to the steel version’s 13 lbs. The wood is American walnut, and calibers are 9mm Luger or .45 caliber both with a 16 1/2" finned barrel and compensator. Add $30 for .45 ACP model.