Abstract: The disclosed invention is an internal measuring gauge having a stationary jaw, a bridge member, a pair of shafts each affixed between the stationary jaw and the bridge member parallel one to the other. In addition, there is a sliding jaw mounted on the two shafts between the stationary jaw and the bridge member with a micrometer head mounted on the sliding with its measuring stem extending through a hole in the sliding jaw and extending toward the stationary jaw. Also mounted on the stationary jaw on the side toward the sliding jaw is attachment means for mounting a precision length spacer to which the measuring stem of the micrometer means communicates to provide extended precision range, beyond that of the micrometer head alone. Further, each jaw includes at least one measuring face which is oriented away from the measuring face on the other jaw.