According to Martin Castle, chief consultant of dangerous goods to PIRA International, "Many in industry assume that if they are in possession of UN tested packaging and a certificate, they have met the requirements of the regulations concerning the packaging of dangerous goods; nothing could be farther from the truth. The UN requirements begin with 12 general statements and only one refers to the UN testing. One cannot overlook the other 11." Although the principal cause of leaks is due to handling, initial package selection by the shipper is most important. Failure to select the right package for a journey has resulted due to shippers assuming that UN packages will perform their job unimpeded. Therefore, Castle states that when purchasing a steel drum, "a shipper must not go to a drum company and only say ‘ I want an X drum for a product ’ They should say ‘I want an X drum for a product which will be shipped all over the world and needs a packaging that will minimally meet the UN criteria and will not be unduly affected by vibration, temperature, pressure, various types of handling equipment, and the like." In all, the selected package must be able to successfully transport the contents safely to their destination and a cushion of safety is wise to incorporate into every drum purchase.