DDoli wrote a question about MontBell U.L. Super Spiral Hugger #1 Down Sleeping Bag: 15 Degree on February 11, 2012
Is it the foot adjuster?
In the old model UL Super Stretch Bag, the foot adjuster exist.
MontBell bags feature a unique foot adjustment system. A drawstring has been added to the last baffle, allowing the user increased adjustability. For shorter users, the last baffle can be simply closed off completely, reducing the amount of empty space to heat.