This is a Hogue Revolver Grip known as the Rubber Grip, model 19000.
Hogue's Monogrip for S&W K and L Frame Round Butt Revolvers is molded from a durable synthetic rubber that is not spongy or tacky" but gives that soft recoil absorbing feel" without affecting accuracy. This modern rubber requires a completely different molding process than ordinary neoprene and results in a much superior grip. The material they use does not come apart or deteriorate and is resistant to all solvents and oils used around firearms. Hogue Grips give you a lasting precision fit and durability that will provide years of dependable service. The flexibility of their materials and molding process has allowed them to produce superior rubber grips with features that out perform all other makes. Excellent for competition and concealed carry use.
Features:
Fits S&W K and L Frame Round Butt Revolvers
Proportioned finger grooves
Unique cobblestone texture
Ambidextrous palm swells