Door glass, vent question

[tazattitude]

There is a gasket that goes on the edge of the vent and the bottom of the glass before it actually goes into the channel. This would hold it into place and keep it come coming out. I can reuse the door glass gasket, but my vent is pretty deteriorated. Where can I get this? I seems to be specific for the vents since it also is the shape of where the handle goes on the vents.

Thanks in advance