From The Manufacturer/Wikipedia/People Smarter Than Us:
The legendary Simmerling is one of the smallest .45 ACP's ever made. This incredible vest pocket pistol has a 5-shot capacity, and the first round is carried in the chamber ready for instant use just like a revolver or a larger frame .45 Auto. The LM4 weighs in at just 24 oz., and is only 5.2 x 3.7 inches in size with a thickness of 1 inch. The LM4 will be produced in limited quantities.