Abstract: The invention provides a removable partition or envelope device that can be placed over the seatbacks and headrests of a convertible automobile to create a barrier to air that would otherwise flow between, around or over the seatbacks, thereby extending a wind-blocking surface beyond the normal cross-section of the seatbacks and headrests themselves. The windbreak can be constructed of leather, fabric, vinyl or other appropriate material, and may include stiffeners or ribs to enhance the barrier's structural integrity and keep its shape against the wind. The windbreak may be manufactured in predetermined sizes to fit particular automobile seat applications, or it may be made of expandable material to fit a variety of seat/headrest combinations. Alternatively, the windbreak may incorporate a means for adjustment, such as a variable overlap portion, to enable the user to specifically fit the device to the seatbacks in his vehicle.