Thanks to the bags spoon form it offers plenty of room for legs and shoulders, so you can sleep on the side, tummy and turn around in the bag without feeling uncomfortable and cramped which is usually the case with mummy style bags.
Depending of the version you choose, the weight can be as low as 0.6 pounds for a small summer one up to 2.1 pounds for an extra-large one suited for the winter camping. Either way you will barely even feel that you have it with you.
Since you can individually order the specs that suit best for you it take up to two weeks for the item to be made just for you and shipped. Alternatively you can buy an already made one but the choice is limited.