Thermoplastic polyurethane, often abbreviated TPU, is a class of polyurethane which are made up of thermoplastic elastomers. Their structures usually feature linearly segmented block copolymers that are made up of soft and hard segments. The desirable properties of thermoplastic polyurethanes include elasticity, resistance to oil, resistance to grease, transparency, and resistance to abrasion. TPUs are widely used in power tools, medical devices, sporting goods, footwear, caster wheels, and inflatable rafts. Another notable application of thermoplastic polyurethane is in cable and wire jacketing.