Dolomite One Bag Size:Regular the NNN system hugs your Size:XL the NNN system hugs your boots while you lay fresh tracks We recommend purchasing the larger size if you're on the fence the Heatseeker Eco lined Dolomite One Bag is the 3 in 1 marvel you're searching for Top layer features 50 degree rated synthetic insulation for versatile use in warmer weatherMid layer features 30 degree rated synthetic insulation for cool nights in the outdoorsThe two layers can be paired to get a 15 degree bag for maximum versatilityZippers open from the bottom to allow for extra ventilationWatch pocket includedRectangular shape is super roomy for a super comfortable experienceComfortable fleece lining on the mid layer is super soft and makes you want to slide right into the bag