This vango ultralite pro 300 sleeping bag is a fantastic choice of lightweight and compact sleeping bag that offers an excellent level of warmth and comfort making it a great 3 4 season sleeping the ultralite pro range has a trilateral construction which includes a thermal reverb which redirects heat radiated from the body back to you and has 4t synthetic insulation which is an innovative synthetic insulation that traps air into its patented channel structure to improve warmth to weight ratio th