Product review (5 stars): No complaints. It's nothing fancy, but it's cheap and works fine. Make sure you measure your air gap before buying.
It's plastic, but the "chrome" plating looks pretty good and won't rust. Plus, you can't argue with the price.

The "tall style" description might make you think it's larger than it is. It's only 2.5" tall with a 1.8" diameter, which is exactly what I needed. However, many of the dishwasher air caps sold on Amazon are larger, so don't let the "tall style" description make you assume it will fit if you have a large air gap. Make sure you measure before buying.