Mitragyna speciosa is an evergreen tree that can grow to a height of 25 m (82 ft) tall and the trunk may grow to a 3 ft (0.91 m) diameter. The trunk is generally straight and the outer bark is smooth and grey.
Overall though, metal is a much better option than plastic. In most cases, it is much more effective and reliable, and the right choice of metal will avoid the pitfalls of rust or weakness. Aluminium, steel and stainless steel are the three metal gutter materials for guards that homeowners can choose from.
When talking about the best material for higher standard tensions, the strongest and most secure is not, unfortunately, the cheapest. In common bridges, pure steel ropes, with few more improvements/supporting, are usually used to support bridges and ease weight on the tension. But it's not necessarily the strongest. Boron fiber, although not very practical since it's very expensive, is probably one of the strongest tension materials there is.