A 6 inch connector (m x m) would not fit my baby bear. I mod everything, so I have a big enough hammer to do this. To get by for now! Next year I will have all new pipe(piece by piece @ Sutherlands sale days) and I've decided to use doublewall from duravent. The first piece I got was the stovetop adapter #8679 (with the damper). The flange inside the trim collar measures 5 5/8 and was a perfect fit. The 1677(single wall) measures 5 7/8 @ the crimp to fit thin wall and stoves with a 6" outlet. I'm using a 1672 with a 6" connector into a T w/cleanout cap figuring that the creosote won't leak on the horizontal. Also using cement. Thanks to all members providing links and info.