Che Posted
"Plus the thin ones will break with good contact"
I am not the cleanest driver as the racers in Denver will tell you. Last year I went through several arms until I made this change.
First the thickness does change from arm to arm. I by 3 pair and match the thickness. Sand the edges of the ourside of the arms and then use super glue on the edge. I have only broken one in the last 10 weeks of racing. (tried a 10 turn mod motor, hit the wall way to hard)