These are the Upper / Trailing spark plugs on the 13B Rotary engines.
Safe for Stock Port / Street Ported motors.
Some people prefer using BUR9EQ for Leading and Trailing spark plugs.
NGK V-Power spark plugs are commonly used in many high performance engines. These are the only spark plugs with the V-Groove technology. By reducing the surface area of the nickel electrode tip closest to the ground strap, ignitability is improved while spark voltage requirements are reduced.