The 20" Cascading Falls package comes with materials to build up to a 6-8ft stream varying in elevation up to 2ft high that disappears into a bed of gravel where it is recirculated back to the top of the falls. Ideal for small spaces and an easy weekend project. Perfect for anyone looking to add an element of water within their landscape. Great for small spaces & corners. You can make a stream approximately 7' long with this kit.