Replacement White or Black Nylon Band for 40 MM Smoke Marking Projectile
This plastic band engages the rifling of the launcher barrel, imparting a nice spin stabilization to rounds in flight.
The base screws into the top portion, and is made to keep the plastic band in place on launch. The aluminum inside the band is knurled to keep the band from spinning in place. The base fits tightly into the top, and with hand tightness should not come loose during launch or flight. The rifling acts on the band, which is attached to the top of the projectile, so it will not loosen the base.
The nylon type plastic band is replaceable, so after you wear one out, you can put a brand new one in place, and keep on firing.