Standard 10 x 20 x 2 1/2 inches deep propagation trays with slotted bottoms for drainage. (See photo). I think most garden centers carry them, especially in the spring, or eBay. Haven't heard from Dennis in a long time; I assume he's still down in Ecuador?Yay besseae (v. dalessandroi)! How deep are the trays? I wonder where Dennis is, probably laughing at us living here in a 3rd World country!