US Patent 7849534 Sleeping bag with vented footbox

A vented sleeping bag comprising an elongate shell defining an inner volume sized and shaped to receive a user therein. The shell has a head end, a foot end, left and right sides extending longitudinally of the shell, an overlying portion which overlies the user, and an underlying portion which underlies the user. The overlying portion of the shell has at least one vent. A closure is selectively movable between a closed position for closing the vent and an open position for creating a vent opening for ventilating the inner volume of the shell.