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.
If esthetics is not a concern (for example, with back molars), gold is the best option. Porcelain inlays and onlays offer the best esthetics and are often used in the smile line areas. Resin materials may be the best option for people who grind their teeth and/or those with a misaligned bite (malocclusion).