100% waterproof and leakproof. Hygienic, easy to fit and easy to clean. Internal corners where two Aquaboard panels meet are best finished with our two-peace internal corner kit. Installing the corner pieces creates a watertight joint and an aesthetically pleasing finish with angles that are easier to keep clean. Note that this corner piece is intended for 90° corners. The back piece is attached to the wall with adhesive. The leading edge of the panel to the left of the joint is fit into the integrated slot and attached to the wall. The process is repeated with the panel on the right. Both edges are then covered by the joint with only a small gap between them. The second piece, a finish trim, is inserted into that gap to create a flat surface. Guaranteeing a watertight seal in the corners of your shower installation is the purpose of these corners. You can install panels without them and simply seal up the joints, but the finished product will not look as good nor will it necessarily be waterproof. Installing these corners is the best way to insure no leaks. First time buying wall cladding? Learn more and compare products here.