The sleeping bag liner has a dual fabric construction, with Thermolite fabric panels in the torso and foot areas to increase warmth. The liner is also ergonomically designed to hug your body, keeping you warm and minimising cold spots within the liner. Sea to Summit have also made this model shorter than the Reactor & Reactor Extreme, with a 183cm body length to accommodate female users, youths and shorter users. The liner includes a handy 14 x 10cm stuff sack for storage and weighs in at 268g, so you can easily pop it inside your rucksack or camping bag to prepare yourself for a range of weather conditions.