Excellent chairs!  My wife and I sit out on the lawn, in these, every afternoon!  We added some generic patio furniture cushions and I lashed an inexpensive beach umbrella between the backrest and arm, which made them even more comfortable, even in the mid-day sun.  That might be an idea for an upgrade--drill a mounting hole and add a clamp on the back support, or armrest, for an umbrella.

PLEASE make some matching Adirondack footstools/ottomans!