All A.B. Biller shafts are stainless spring steel manufactured from a special alloy originally developed for the U.S. Navy. Heat treated to Rockwell 44C, these shafts produce a unique combination of hardness and spring tension. Line shafts 42" and longer come with 3 grooves to accommodate 3 bands if desired. 6mm threads to accept most tips on the market. Will also fit original Seahornet spearguns which are now distributed by Tusa and most recently distributed by Spearfishing Specialties.