I only inflated this indoors once for a test. I'm selling it because I've been using a different air mattress and this one has been sitting unused. It's a mummy-shaped silver M size (183cm x 58cm). Size: R5.8-M (183x58x7cm) Features: Lightweight, Compact Brand: Naturehike Mummy Type - Silver Product Dimensions: 183cm length x 58cm width x 7cm thickness About this product: [Utility Model Registered] The Naturehike high R-value mat uses a utility model registered structure and prevents heat loss due to radiant heat transfer with its aluminum material's anti-radiation function. Each independent air chamber is separated by a film, preventing heat loss due to convective heat transfer caused by air circulation. The interior design features a multi-layered three-dimensional heat reflection structure to withstand the cold. [Compact and Ultra-Lightweight] The Naturehike high R-value mat is made of ultra-lightweight material, with a total weight of only about 500g. Double size (refer to the table on the next product description page for each size). Also, the storage size is very small, effectively reducing the burden during mountain climbing and camping trips. [SGS Certified] The Naturehike high R-value mat is SGS certified, and r 5.8 and r 8.8 are suitable for all seasons and extremely cold environments. (*It is recommended that those who are sensitive to cold purchase a mat with an R-value 0.5 higher than the normal applicable temperature.) [Thick 7cm for Comfortable Sleep] The Naturehike high R-value mat has high cushioning and a thickness of 7cm, eliminating the unevenness of cars and the ground, making it difficult to feel the unevenness, ensuring a comfortable sleep. Also, you can inflate it to your preferred firmness and adjust the thickness from 7 to 9cm.