Material 100% Seamless Sanko 4130 Chromoly Tubing. CNC’d Seatstay Bridge with Kink Badge Inlay Anti-Slip Interior Dropout Knurling. The double butted toptube and downtube with gussets on both, ensure plenty of strength in the front end while the chainstay and seatstay bridge designs allot for generous tyre clearance while adding as much stiffness as possible.