They are Eco Arbor Designs and they have a plastic backing that snap together. They hold up well under the right application.

Interlocking tiles are a great idea if you don't have much slope on your rooftop. But if you want the deck to be perfectly level then you would need to use a pedestal system. And another alternative to natural wood tiles are 3/4" thick porcelain pavers which are now available in a number of wood look designs. And porcelain won't fade, is stain resistant, totally fireproof and scratch resistant