Separately available protectors and/or back protectors come in a number of varieties, but all have one thing in common: they are the main protection in case of impact or a fall. It is the protectors that turn motorcycle clothing into protective clothing, because they absorb and disperse energy.
There are several (proven) technologies, of which the two best known are D30 and SAS-TEC. This new generation of protectors is quite hard and becomes more flexible the longer they are worn. The material of the protector becomes softer thanks to the body temperature of the person wearing it, without compromising the level of protection in case of impact.
Why separate protectors?
Indeed, your jacket or pants already contain one or the other when you buy them. However, you can always fit a better/other protector for extra protection.
Some clothing comes standard with a number of foam rubber protectors, which you can upgrade yourself in the provided compartments.
A third option are the (back) protectors that you can wear underneath the jacket. The advantage is that they fit your back perfectly (and not just sitting on your back, inside the jacket).