My recently acquired Logan 400 9" lathe was originally equipped with and currently uses lantern-style or rocker-style toolholders. While effective, they are a pain to work with because they can be awkward and difficult to adjust properly, and by properly, I mean that the cutting point of the tool must be at the centerline of the lathe. This is because the cutting geometry must be correct to be not only efficient, but capable of producing a good finish. This is the toolholder (and wrench). The long serrated piece of metal is the rocker that is used to adjust the vertical angle of the tool that holds the cutting bit. The threading tool is inserted in the toolholder. Of course, the toolpost is intended to be held in the compound slide of the lathe. The benefit to this style of toolholder? They are usually included with vintage lathes when you buy one. The downside besides the inconvenience of adjustment? The tools themselves are about $30 each and only accommodate one size of HSS