What happens is the dude arrives with a new piece of glass that has the rubber piece preattached since that's how they come. Look at a windshield closely.. see how it's black for about the first inch or so around the edge? Under that is where the glue to hold it into the body of the car is located. The rubber does nothing.. it's decoration. Since yours is old and shrinking..you'll fight, glue and scream about it for a long time until you simply replace the window.