Flat Bottom Set of Humbucker Rings: This is a typical set of plastic mounting rings found on most 2 humbucker guitars. It is comprised of 1 high and 1 low ring. These are perfect for Gibson and Epiphone flat-top electrics, and other humbucker guitars with flat tops (not curved or arched). Part number HMRB Set. Flat Set: Low = 9/64 inches - 13/64 inches High = 19/64 inches – 3/8 inches Interior Dimensions: Pickup cutout width = 1.5 inches (38.2mm) Pickup cutout length = 2.76 inches (70.2mm) Exterior Dimensions: Exterior width = 1.76 inches (44.7mm) Exterior length = 3.50 inches (89.1mm) Exterior height tall side = .375 inches (9.5mm) Exterior height short side = .295 inches (7.5mm) Height holes center to center = 3.07 inches (78mm) Mounting holes center to center length = 3.185 inches (8.09mm) Mounting holes center to center width = 1.43 inches (36.3mm)