I've seen these but they were home made at a local machine shop. They consist of a piece of intermediate conduit approx. 4 - 8' long with bushings pressed in each end. There is a 3/8" or 1/2" shaft that passes freely all the way through the pipe. The shaft is quite a bit longer than the pipe and is held centered by the bushings. On one end of the shaft is welded the sawed off end of a bit extension. This is where you attach the hole saw bit. The other end is chucked up in your drill. To use you just strap the conduit to the wall where your service mast will go, level it, chuck the shaft up to your drill, and go. It drills a perfectly aligned hole through both the soffit and the roof. Works great on spec homes where you can just punch them all out in a row.
