Leckey Mygo User Instructions page 45

10.5 Backrest height
The overall height of the backrest can
be adjusted by loosening the two socket
cap bolts, then positioning to the required
shoulder height of the user. Once in position
the socket cap bolts should be retightened
securely. The height can be fine tuned when
the user is in the seat.
Use caution when adjusting to minimum
setting as fingers could become trapped
between moving and static parts.