A. It is made of durable material and is practical to use. B. Indicator extension rod with M2.5 thread, available in lengths of 20mm, 40mm, 60mm, 80mm, and 100mm. It is applicable to interchangeable tools such as dial gauge altimeter, depth gauge, etc. The effective length does not include the threaded rod. C. The diameter is 5mm / 0.1968 inches. The extension rod has M2.5 threads at both ends. D. L25: Length 25 mm / 0.9842 inches. L50: Length 50mm/ 1.9685 inches. L75: Length 75mm/ 2.9527 inches. L100: Length 100mm/ 3.937 inches. E. The color is silver. The material is stainless steel. F. Package Contents: 4 * Dial Digital Indicator. Only the above package content is included, other products are not. G. Note: Light and different displays may cause the color of the item in the picture to be a little different from the real thing. The measurement allowed error is +/- 1 - 3cm.