Stewart golf x seriesf1 umbrella holder this umbrella holder is designed for use with both the x series electric golf trolley of any age and the f1 lithium electric golf trolley when used with the f1 lithium then the umbrella holder simply screws into the thread location already on the handle for use with the x1 x3 x5 or x7 fit the black ball into the centre ball holder location this is secured in place by a backing plate and screw this black ball can be left in place at all times a