These new products are intended for use as bends with the Deep-Cut river, dirt road, and cobblestone road strips (example shown below). Simply cut them to the desired angle of bend with a craft knife or scissors.
The associated mouse-mat terrain strips from Deep-Cut enable a river, road or track to be quickly laid across the top of your terrain mats. They are 6-foot (183cm) long by (9cm) wide, lay flat on the table, and are non-slip. Here's the Dirt Road strip.
You can find the bends and associated strips in the BigRedBatShop! The bends are light in weight and cheap to post internationally.