It is part of the Centennial line of revolvers introduced in 1952 to mark the 100 year anniversary of Smith & Wesson (though this particular model was not introduced until 1990). Because of its place in the Centennial line, this gun is also known as the S&W Model 442 Centennial. Recently, Smith & Wesson dropped the Centennial line (as their Centennial was over 50 years ago) but continues to produce this gun as simply the Model 442.
The 442 is a Smith & Wesson J-frame revolver. It has a 5-round cylinder and a 2-inch barrel. The gun was constructed entirely of stainless steel until 1995 when it was switched to aluminum and designated "air-weight". For this reason the gun is also sometimes referred to as the S&W Model 442 Air-weight.
Unlike its counterpart, the Smith & Wesson Model 642, it features a blued finish.