Our Oslo has two what are either 1/4"-20 bolts (or the godless metric equivalent) in threaded holes in the flue collar, one assumes for the purpose of positively securing the flue pipe. It seems an odd setup and choice of fasteners. If I just put the pipe on and screw the bolts in, they are large and powerful enough to distort the pipe, so it is no longer a good fit and leaks. If I just screw them in as tight as I can without distorting the pipe then the pipe is not securely enough fastened for safety. So it would seem the pipe must be drilled to accept the bolts. But to drill it (since the threads are in the flue collar) one must assemble the pipe in the collar, mark it, remove it and drill it then reinstall it and hope the holes still line up perfectly so the bolts will go in. Or I could drill the holes oversize, but then the pipe will be able to move around more, as the bolts are acting as locating pegs rather than as fasteners (there is no tension holding them snug against the collar since the threads are on the collar not the pipe). Most stove I have had have just a smaller, untapped, hole in the same location. Once the stove is installed and the pipe in the right position, one simply drills a hole through the pipe using the hole in the collar as a guide, then fastens the pipe in place with a self-tapping sheet metal screw. Quick, simple, inconspicuous and makes a good seal. You can't do this gracefully with the Jotul setup since, because of the size of the hole, it would take a huge sheet metal screw. Anyone have any thoughts what Jotul could have had in mind?