Allows for + / – 35mm of vertical deflection in a sealed unit. Utilises a vertical arm to avoid service clashes. Connect to the head track (min .75BMT Steel or 1.3mm Aluminium Section) with 10 gauge wafer tek screws or timber top plate (90 x 45mm SG8 Radiata Pine or Douglas Fir) with 10 gauge 35mm wood screws.