There are four variations of the 51, two in .380 and two in .32. I once had examples of all of them, but at present I have only the .380s. Probably the most ergonomic pistol design ever made, and very thin. Needlessly complicated for a .32 or .380 pistol, but it works well. The much more recent Remington R51 in 9mm has the same design but it didn't work out too well.