Help™ Rear Back Glass Wiper Arm by Dorman®. Lenght: 15.5″. Finish: Black. Attachment Method: Threaded Stud. Material: Plastic. Wiper End Type: Snap In. A streaked windshield isn’t only aggravating, it’s unsafe. If new wiper blades aren’t fixing the problem, your wiper arms may be the culprit. Properly functioning arms are essential to a clear and clean windshield. Count on Dorman to help restore the efficiency of your wiper system and your vision of the road.