RT (Rigorously Tested) Technologies was established in order to build the most consistent graphite shaft on the market today. The hardest part of building the right golf club for that one, individual player is finding a shaft that will react the same way each and every swing. * * Only (1) different head weight and (2) bore depths will change this shaft's performance. RT golf shafts use (1) a head weight of 200 grams and (2) a bore depth of 1 1/4th to 1 3/8 inches. Club builders using these guidelines will have shafts that are amazingly consistent.