For a great nights sleep in the outdoors, the Serenity 350 is a warm, comfortable 4 season sleeping bag. Providing excellent protection from the cold, this mummy shaped bag is filled with thick insulation for maximum warmth. An adjustable insulated hood and inner zip baffle ensure the heat is retained, making this an ideal sleeping bag for any cold weather adventure. Synthetic insulation is an ideal choice for sleeping bag filling. The Serenity sleeping bags filling of SFX spiral hollowfibre is specifically designed and tested to keep you warm even during the coldest times of the year and holds warmth well when wet to combat tent condensation. It also compresses easily, packing away into a compact stuff sack and quickly regaining its shape and loft when opened.. The Best Materials. The materials used, which include Outer: 210T ripstop polyester, Lining: 210T polyester pongee and Filling: 350gsm SFX spiral hollowfibre, are commonly used in outdoor gear due to their ability to withstand