Two-Shot Instrument Control Knobs Davies Molding Two-Shot Instrument Control Knobs are available in Slide, Instrument, Pointer, and Skirted configurations. The knobs are available for special applications with a variety of sizes and styles to meet a wide range of needs. They are available in both phenolic and thermoplastic materials and have a sophisticated and distinct appearance. Davies Molding Two-Shot Instrument Control Knobs sizes range from 1/2' to 2-1/4' in diameter.