Control Length 29-1/2″. Wheel Control Assemblies. – Turn upper wheel for horizontal position. – Turn lower wheel for vertical position. – Distance between wheels: 2″. – Maximum ceiling thickness: 3″. Lever/Gear Control Assemblies. – Aim handle for horizontal position. – Twist handle for vertical position. – Maximum ceiling thickness: 3-1/2″. Order head and wheel or lever/gear control assemblies separately.