The extension has been well made with quality casting and machining. The only issue that others have reported was the length of the two set screws that hold the Forstner bit in the tool. They were about 2mm longer than necessary which resulted in the screws protruding beyond the screw holes and increasing the diameter of the tool. A few minutes on the grinder and the bolts were perfectly shortened. You can also find the right length at a good hardware store if you don't have a grinder.