This ad is for 1 (one) slide adapter that adapts an 18MM male slide bowl for use on a smoking device that would normally accept 14MM male slide bowls. This adapter has an 14mm Male joint on one side that would be inserted into the 14mm smoking device, and the other side of the adapter is an 18mm Female where you would insert the 18mm male slide bowl. The adapter itself is over-all is about 3" long, but when in use the 14mm male portion would be in the stem of your water pipe and only 2" of the adapter would be protruding past the original length of the down stem. This unit has good quality thick glass construction and will allow you to use many more accessories on your current pipe.