A 4.2-inch offset spatula is a tool commonly used in baking to apply frosting, buttercream, and other coatings onto cakes, cupcakes, and other baked goods. The "offset" feature refers to the design of the handle, which is slightly offset from the blade. This feature allows for greater control and maneuverability when spreading coatings onto cakes, especially in hard-to-reach areas such as the sides.