There are a few things to consider when choosing a downstem for your Bong or Waterpipe. The first is the joint size - you'll need to make sure that the downstem sizes fits snugly into your water pipe's joint. The second is the length - you'll want to choose a glass downstem that is long enough to reach the bottom of your water pipe but not so long that it makes it difficult to clean.
Finally, you'll need to decide on the type of glass downstem you want. There are two main types - diffused downstem and non-diffused downstem. Diffused downstems have slits or holes that help to diffuse the smoke, while non-diffused bong downstems do not.
