These Wide Mouthed skimmer boxes can be built into the walls of a concrete pond or can be used with a pond liner and the clamping plate to secure the skimmer box is included in the kit.
Please note that a skimmer also requires to be connected to a filtration unit of some sort.
The Hidroclean is highly recommended for this purpose and is easy to fit ...and an ideal pump for this system would be the Oase Aquamax ...used as a dry surface pump and not as a submersible.