The biggest determining factor for shield application is the rating if you have a G-FORCE Racing Gear helmet with a Snell rating of M95 or SA95, there are no longer shields produced as the helmets have been out of production since 1999. For helmets with Snell ratings of M00 and SA00 there are 2 possible options.
If the shield is held in place with a black plastic plate over the shield mount, you should use shields 8401(Clear, Out of G-FORCE stock but dealers may still have), 8402(Smoke), 8403 (Mirror), or 8405 (Blue).
If you remove the shield by lifting and pulling levers to release the shield, you should use shields 8501(Clear, Out of G-FORCE stock but dealers may still have), 8502(Smoke), 8504 (Amber) or 8505 (Blue).
For helmets with a Snell Rating of M05 or SA05 you will use the 8600 series shields, 8601 (Clear), 8602 (Dark Smoke), 8603 (Mirror), 8604 (Amber), 8605 (Blue) or 8606 (Light Smoke).