Swivel reamer (adjustable reamer) is a tool that can adjust the blade diameter even among cutting tools (reamers) used to finish a pilot hole drilled with a drill or the like to a dimension and shape determined with high accuracy. The unit is books. The shank diameter and the adjustment range are finely set according to the size, and some of the smaller ones have fewer blades. It is an essential item for drilling holes in pipes and seat tubes because it can easily adjust the inner diameter. Measure the place and size to use, and choose the right one.