Snap-Lock Black Steel Adjustable Stovepipe Slip Connector - 6-Inch Diameter

The trick to assembling snap lock pipe is to lay the pipe on a flat surface, then push the male end of the seam straight down into the female end until it hooks into position. Once you release the pressure, the male end should hook into place and the pipe will form back into a round shape. Please keep in mind that you may have to exert a good deal of pressure to get the two halves to hook together and the pipe may flatten somewhat while you assemble it. However, it can be rounded back out fairly easily.