Park Tool Oversized Adjustable Saw Guide - SG-7 Accurately guides a hack saw to cut steerers, integrated seat posts The SG-7 features a hardened steel body and molded contact pads to protect tubes and frames. Even airfoil shaped seat posts up to 3.5 (89mm) or round tubes from 1-1/4 (32mm) to 1-1/2 in diameter (45mm)