From The Manufacturer/Wikipedia/People Smarter Than Us:
The Ruger SP101® revolver boasts the strength to handle the powerful 357 Magnum cartridge in a controllable, small-framed double-action revolver. Among the most powerful small-frame revolvers on the market, they are engineered for solid performance. Featuring a recoil-reducing grip, the SP101® is comfortable to shoot and perfect for personal defense or field use.