Prestretch film is a blown film which has already been stretched during manufacturing to achieve a higher level or strength and memory. The process stiffens the film, resulting in a greater rigidity to the load during the wrapping without having to apply a lot of force. Prestretch film is also double layered. This added layers means that it snaps back (or contracts) like an elastic band on the load after it has been applied (with just a little added stretch) making it very strong.
