The SOLO-QUILT v4.0 sleeping bag has been available for pre-sale on the Japanese crowdfunding site “Makuake” since December 18, 2020, and is gaining popularity with sales exceeding 10 million yen. The features of SOLO-QUILT v4.0 are, as the name of the product implies, an open back type called a quilt, which makes it lightweight, and a unique insulation material that allows it to dry quickly even when wet with dew or sweat. The product itself is unique and good, and one of the reasons for its popularity is that the product introduction page includes comments from mountaineers and trail runners who have used it.