The HKS M Series Speedloader drops cartridges with just a slight twist, loading the entire cylinder of your revolver. The principle is simple, strong metal points hold cartridges securely in the loader until you release them with a turn of the knob. The knurled aluminum knob allows for a sure grip under the most stressful circumstances and the also makes the speedloaders easier to grab out of a pouch. Fits medium and large size speedloader case Loads .41 Mag cartridges into revolver instantly Works best with cartridge jiggle Compatibility: S&W 57 and 58, Ruger Made in USA