The springs that tension the vent window get old, rusty, or break. If your vent window won't stay open this little prop will fit over the vent window handle and allow you to prop it open. Designed in TinkerCad, it is simply a box with a plastic arm to prop the window open.

The file contains one left side and one right side prop. These fit my 1971 and 1977 MGB Roadsters. Earlier models may have different vent window handles.