LiftMaster Curved 178B35 and Straight Arm 178B34 Garage Door Opener Arm Assembly Kit for Residential Operators LiftMaster Garage Door Opener Arm Assembly Kit for Residential Operators LiftMaster Curved (part # 178B35) and Straight Arm (part # 178B34) Includes fasteners and bracket as pictured. Replacement Part Please check your owners manual to see if this part is compatible with your opener.