Often called the glass anti-rattle kit. These are the vertical pieces in the door that support the glass in the vertical movement. Our reproduction channel is not the fold over 510 glass run variety. Our weather-strip is molded like the original in "U shaped" channel form like the original. We like this channel as it does not bind the glass. NOTE:Enough material is supplied to do all 4 tracks, 2 front & 2 rear in one continuous length piece.