This wrench is for the rod bolts on some large Mcculloch saws. It is 6 spline. I have been working on saws for over 30 years and it is the only one I have ever had. Rare for sure so $20 gets it to your door or PO. It is marked Allen super-torq st-1620K-09 Not chipped, cracked or tweeked, just old. Splines are good. Mike