This ad is for 1 (one) slide adapter that features a glass 18.8mm to 14.4mm slide bowl adapter for your water pipe/ hookah. This adapter has an 18.8mm Male joint on one side and a 14.4mm Female joint on the other. This adapter is designed to plug into a 18.8mm water pipe stem an allow you to use 14.4mm male stem slide bowls in what otherwise would be a 18mm water pipe. The adapter itself is over-all is 2 1/2" long, but when in use the 14mm male portion would be in the stem of your water pipe and only 1 1/2" of the adapter would be protruding past the original length of the down stem. This unit has good quality glass construction and will allow you to use many more accessories on your current water pipe.