This is the Park Tool SG-7.2 Oversized Adjustable Saw Guide. The SG-7.2 accurately guides a hacksaw to cut aero-shaped seat masts and seat posts up to 2.75" (70mm), as well as fork steerer tubes and other round tubes from 1-1/16" to 1-3/4" (27mm to 45mm). The SG-7.2 features two different cutting slots--standard and carbon cutting blade widths--in a hardened steel body with molded contact points to protect tubes and frames. Features: For aero-shaped seat masts and seat posts up to 3.5" and fork steerer tubes from 1-1/4" to 1-3/4" Hardened steel body with molded contact points to protect tubes and frames Features two different cutting slots (standard and carbon cutting blade widths) Hardened steel body with molded contact points to protect tubes and frames