Hello First I want to say this is not a permanent venting solution and it is not recommended for unattended use. To test a stove without too much fuss, I found a 2-3/4" ID muffler adapter pipe at auto zone. The OD is the same diameter as a pellet stove exhaust vent flange. By using a radiator type clamp to clamp down the 3" flex venting and some foil tape, it can be attached to the stove adapter fitting in the exhaust system. The other end is the easy part. Just add a flex pipe adapter and connect that to a stove adapter. Great for a temporary connection that is safe as long as the stove has the required clearance and floor protection. Maybe I am a little excentric but Just think of these 2 common scenarios: LOL 1. "Hey dear your buddy is coming over with his pellet stove again" "Ok dear, I will go get the extra hearth pad and extender!" 2. "Hey dear it is so cold and stormy, I wish we could move the stove out to the middle of the room tonight?" Ok, dear I will get the extra hearth pad and extender" LOL Actually, I am using this piece to test a stove, so I do not have to re-adjust the height of the venting to accommodate the vent flange just for a one time test.