Sea to summit tpu guide waterproof case for large smartphones description our tpu guide waterproof phone cases are a slim yet robust solution for protecting and using your phone in any conditions rf welded thermoplastic polyurethane tpu and the zip lock triple roll velcro closure keeps this soft case both watertight and slim the tpu is pvc free strong flexible durable uv and extreme cold resistant the latest addition to the line has been sized to accommodate larger sized phones