Comments about Planter Casters, Set of 4:
I bought four sets of casters for my two large Terrazza Trough planters (16 in all). My only complaint is that they don't snap into the containers, but merely sit in the holes provided. So, they fall out easily when you're trying to position them all. But, once they are put in, they're fine. Just be sure to buy two sets of casters for the large rectangular planters. I made the mistake of thinking that four would do, but then realized that the weight of the container really needs eight. Also, due to the design, you really can't find casters from the local hardware store that would work. They make wheeling the containers around the deck a breeze.