The Blue Restrictor Plate by ARC is the industry standard for legal restrictor plates for AKRA and NKA Clone Box Stock Classes.

The ARC .550" blue restrictor plate is designed for the 196 Clone Box Stock for other classes, i.e., Predator 212 Box Stock; check with your track's rules for class structure and legality. 

NKA Restrictor Plate Rules

40.4.36: Restrictor Plates

40.4.36.1: Modification of the restrictor plate is prohibited. The anodizing shall not be removed around the holes. The plate must be flat; holes must be as produced with no rounding of the edges. All holes must align perfectly with a stock ARC plate. If a restrictor plate is used, there must be a gasket on both sides.

40.4.36.2 Available restrictor plates, checked with blade type NO-GO gauge.

Blue: .550" Purple: .500" Green: .425" Red: .375"