The U.S. Marine Corps is conducting a Sources Sought/RFI market-research effort to identify potential sources capable of manufacturing a high-performance combat boot sock for use with standard-issue combat boots. The sock must be over-the-calf with cushioning, graduated compression, a non-slip top cuff, contoured foot, arch support, gore heel and toe, reinforced heel and toe, and a seamless or low-profile recessed toe closure. It must contain at least 52% wool (25 microns or finer), at least 20% nylon, and at least 1% spandex, with no cotton or rayon, and meet shade and performance requirements in the purchase description. This is not a solicitation; no contract will be awarded from it, and responses are voluntary for market-research and planning purposes only. Based on responses, the Government may plan a future acquisition and may request samples for evaluation.