Stannah Saxon Arm Bottom Moulding (On/Off Switch) Arm Bottom Moulding which incorporates the On/Off Rocker Switch and Key Switch for the Stannah 300 – 400 – 420 – 260 Stairlifts. Arm Bottom Moulding which incorporates the On/Off Rocker Switch and Key Switch for the Stannah 300 – 400 – 420 – 260 Stairlifts.