The MK4B, MK4BL, KMK4BL and Franken-Ruger are great little pistols. A friend of mine had a MK4B with the thumb rest grip, he was left-handed, so he ordered a set of left-handed thumb rest grips and used the flat panels to make it work better for him. I told him to use a set of standard MK2 grips to make it more useable for himself. I am really surprised that they were not more popular. If carried in the right holster it's a great field pistol and if you are a good enough shot it can bag a squirrel with no problem.