This is a jig to open a hole exactly the center.It is difficult to open a hole on the side of a pipe. But you can do it very easily, if you use this jig.How to use:1. insert the pin bush to the hole of the base frame.2. to be bolted the base frame to drilling machine. The pin bush inserted into the hole of drilling machine work table.3. Put the pipe holder on top of the base frame. And adjust the position of the work table to be fit the drill with the hole of the pipe holder.4. Put rubber sheet (0.5t) to base frame and pipe holder.then you are ready to use.