This is a vintage Custom Shooting Products (CSP) Bore Barrel Micrometer, which comes in a wooden box. The micrometer is designed to measure the diameter of a bore, and it features a micrometer type known as a Bore Micrometer. The brand of the product is CSP, which is likely a company that specializes in shooting-related products. This micrometer is a precision tool that would be useful for gunsmiths or anyone who needs to measure the diameter of a bore accurately.

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