Photo shows 3 units. Top unit is simply the left/right end pieces put together. Middle unit is left/right end pieces with one 16" extension module. Bottom unit is left/right end pieces with two 16" extension modules.
Use this 16” Extension Modules to form as large of a waterfall spillway as you’d like! These spillways are ideally suited for forming the headwaters of a waterfall/stream feature. They are designed to be installed inside the liner to prevent leaking. Each piece is extremely rugged and includes heavy plastic grating making it easy to completely hide the unit under rock. Note: you need to also purchase the Left/Right End Pieces to make a usable waterfall.