You can fine tune your armrest height and then snug it down tight with an armrest adjustment knob for Invacare AVIVA FX and Pronto power chairs. Invacare uses this handy little knob for the height adjustment on all of their Pronto series chairs except the M71 Jr., and Pronto R2. In addition, Pronto models models (other than the M91 & M94 that use Invacare's Van Seating) also use this little knob for adjusting the width between the armrest brackets.
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