The Glider Shield is intended to keep gliders from getting into trouble by wrapping their tails around the wheel's axle. If your glider is of a mind to try to wrap his tail around the axle while running, the shield should prevent a world of hurt. The Glider Shield (includes the seam cover) can only be mounted in wheels that have a new inner ring molded into the front and back panels for this purpose. Panels with this ring started shipping in the second quarter of 2011. Panels shipped before this will not work with the Glider Shield. If you have an earlier wheel without the inner rings, you can get a Retrofit Kit that includes the Glider Shield (with seam cover) and the new front and back panels with the inner ring.