Thermoplastic polyurethane (TPU) refers to a class of polyurethane plastic with many useful properties, including elasticity, transparency, and resistance to oil, grease and abrasion. The material is flexible yet rigid. Visually, it looks and mostly feels like a hard case yet when you take it off your device you will find that you are able to maneuver it like a soft case. Cases of this type are very durable.