A brain implant which inhibits nociception, or pain sensation. While it does allow the user to accomplish more, it turns out pain has a purpose. When you don't feel it, you can get hurt really bad really easily.
A Painstopper is a brain implant that will completely eliminate a colonist's pain and any pain-related mood effects. Note that colonists with the Masochist trait get a mood bonus from pain, and this will also be removed by the Painstopper.
Most kinds of pain are temporary and not worth installing a Painstopper for. However, pain from scars is permanent, and some painful diseases such as Sensory Mechanites can linger for long periods of time.
Be careful when using this, as colonists with this implant will not go into shock from pain and will keep fighting until death (most common case), or be incapacitated from serious leg, spine or brain injury. This property can make them valuable soldiers, but requires that you keep an eye on them constantly so you can get them to retreat in time before they receive fatal damage.
In the base game it can only be obtained via trade. With the Royalty DLC it can be crafted using 20 steel and 4 components after the Brain wiring research is completed.