This medium plastic humbucker mounting ring is generally used in the middle position on a three pickup guitar. Also can be used in neck or bridge position depending on height requirements of your instrument. This is angled in height so side closest to bridge is taller than the side closest to the neck or fretboard. This is NOT an arch bottom mounting ring for an instrument with a carved top. Important Specs and Dimensions: Interior Dimensions: Pickup cutout width = 1.5 inches (38.2mm) Pickup cutout length = 2.78 inches (70.8mm) Exterior Dimensions: Exterior width = 1.76 inches (44.7mm) Exterior length = 3.53 inches (89.65mm) Exterior heights tall side = .29 inches (7.37mm) Exterior height short side = .21 inches (5.36mm) Height holes center to center = 3.09 inches (78.5mm) Mounting holes center to center length = 3.18 inches (8.08mm) Mounting holes center to center width = 1.42 inches (36mm)WD Music