Starrett inside micrometers use interchangeable rods for measuring the inside dimensions of pipes, tubes, cylinders, rings and holes. These micrometers are equipped with rods having insulated handles for minimising expansion from heat. They come integrated with ground steel supporting collars that are placed in V grooves for fine adjustments in the measurement range, when used in the horizontal position. Choose from a wide range of these inside micrometers, available in rod diameters of 0.25, 0.375 & 0.625 inches.