We have developed SRDK-101D, a small size two-stage GM cryocooler. The cryocooler has the cooling capacity of 0.1 W at 4 K at the second stage. The cooling capacity is the smallest among our product lineup of 4 K GM cryocoolers as well as the size, weight and power consumption. The cryocooler is designed to operate at a commercial power source of single phase 100 V by connecting its power cable to a receptacle available in a laboratory. This paper presents its product concept, basic configuration, and its performance.