Caliber 41 rim fire. This is probably the best I have ever seen. Retains most all of the original nickel. The hammer, cylinder and cylinder pin retain most all original gold wash as well. Beautiful condition Mother of Pearl grips have a nicely done monogram on the left side. Case is in Very good condition with a cartridge block that holds 15 cartridges with various head stamps. Original key is present. Excellent inside and out!