This product is Teak requires a lot of maintenance.  Expect to oil the entire chair with Teak oil once a year.  This takes about an hour per unit.

Polyurethane, and semi-gloss polyurethane will look good for a few weeks, then fade and look terrible.

None of the issues are specific to this product.  All Teak furniture does this, however I feel compelled to share this as it is a lot of work, and a recurring task, especially if you buy several teak products.