What is TPU?
TIM G It's the plastic the bag is made out of.
JOHN W TPU is an thermoplastic elastomer. Simple description: the case is made of TPU which is a very pliable polyester envelop (feels like vinyl but tougher and doesn't yellow like vinyl). It's works very good, and seals up watertight. I have used mine with a Palm device and an iPhone and both were usable through the enclosure.
CHRISTINE C "Thermoplastic polyurethanes (abbreviated TPU) are a class of polyurethane plastics with many useful properties, including elasticity, transparency, and resistance to oil, grease and abrasion. Technically, they are thermoplastic elastomers consisting of linear segmented block copolymers composed of hard and soft segments." Referenced from online.
I LOVE this product! I work as a nanny & my phone must be near me always. I can count on it being protected from water & anything else that could happen to it. Plus I can hang it around my neck, which I find convenient. You can talk on the phone while it's in the DryPak, which is wonderful. I highly recommend this well-made product.