Piney Mountain .22LR tracers, (unlike most tracers) are non-corrosive and do not hurt the barrel.  

Most .22LR tracer rounds have the tracer chemicals are on the back of the bullet. Piney Mountain tracers are hollowed out in the back, creating a pocket, making it so the tracer compound never makes contact with the barrel.

Because of this, an additional benefit is that they are less likely to start a fire. These .22LR tracers burn for 150 meters and can be easily seen both day and night.