The JLD Bridge Doctor Enhances volume Flattens 'bellied' soundboards A unique solution to a common bridge problem, this spruce device attaches beneath a guitar bridge. An adjustable spruce "pressure post" rests against the tailblock, providing leverage to flatten the soundboard. The spruce block is 3/4" x 1-5/8" x 3-3/8" tall. The 1/4"-diameter tension rod is 9" long. The mounting post has three different positions to accomodate a variety of bridge styles. Screw mount version: This spruce device attaches beneath the bridge via an inlaid screw (a white pearloid dot is included to hide the bridge screw). An adjustable spruce pressure post rests against the tailblock, providing leverage to flatten the soundboard. Better bridge contact and alignment can also enhance sound projection. NOTE: This tool requires a hole to be drilled through the bridge behind the pin holes. StewMac Tech Tip: We recommend the brass pin mount version (sold separately) for 12-string guitars. Installation instructions included.