A Browning design produced by Colt from 1908-1946. The pistol has a striker mechanism rather than a hammer, a design widely used throughout the world. Originally designed with a grip and thumb safety, models after serial number 141000 had a magazine safety that prevented firing while the magazine was removed from the pistol.
Dimensions / Sizes;
Measuring from back side of right panel with grip standing on its butt and the ruler vertical
2 5/32"long x 1 1/4" wide