Shock Recommendation
You are 100% correct. I've been using slotted and drilled rotors for 30 years. The vanes when they are angled, determine the direction of the rotor. But I have seen rotors that are labeled wrong. But if the vanes are straight, you can install them if the cross drill or slots look like the picture on the left below for directional vanes. I always just check the direction with a screw driver.
You are 100% correct. I've been using slotted and drilled rotors for 30 years. The vanes when they are angled, determine the direction of the rotor. But I have seen rotors that are labeled wrong. But if the vanes are straight, you can install them if the cross drill or slots look like the picture on the left below for directional vanes. I always just check the direction with a screw driver.