The 19mm Female/14mm male Bong Adapter is handy and cool bong part.If you want to use your 19 mm cone piece on a 14mm bong/stem , then this the adapter you need.On the other hand ,You can flip this adapter and you will be able to use it on a 19mm male bongs. In other words, if you have a male 19 mm bong , you can use this adapter to fit a 14 mm female cone piece.