Pond Liner 4m x 4m 25 YEAR GUARANTEE
Absolute rubbish had mine 3 years and it's already leaking. The 25yr guarantee: Don't try to claim on it. They'll want you to empty your pond, and prove it's their fault, and also want further proof of underlay ( they're expecting you to buy theirs ) purchase. In other words they've waved 2 fingers at you.
The certificate isn't worth the paper it's written on.