You will always need to have a few essential trailer spares. You cannot be en route to someplace far or near, in the middle of nowhere or at home when you are just about to embark on a journey and find the inevitable need to replace a few trailer parts. Many parts or components will not have sporadic issues and some will give you a fair bit of warning for a while before completely breaking down or malfunctioning. The parts that can suddenly break down or malfunction will call for trailer spares and you will need to be a tad familiar with how you can work with them, especially the disassembling and assembling or installation.
Since trailer spares are likely to be stored for a considerable period of time, you need them to be completely immune to the usual threats so they can be still used when needed. This means you will need materials that do not rust or rot. There should not be any corrosion whatsoever. It should be noted that many materials can respond to heat, pressure and chemicals. You will keep your spares in a safe place but there can be a myriad of exposure in due course of time. Steel and aluminum fare quite well in such situations but composites are a tad better.
Composites are durable materials. It is flexible as a material so many types of spares or parts can be made and you can rely on the durability. The material is strong enough to endure the rigors of daily use so if you are unfamiliar with such spares and hence wondering if they will be a good choice then you can rest assured. Trailer spares made of composites are lighter than those made of steel and aluminum. Hence, if you have to carry quite a few of them when you are travelling, then the effective reduction in net weight will be satiating.