Test Plugs insert into pipe ends to stop fluid flow, so that pressure tests can be carried out on piping. Wolverine Brass crimp brass pex fittings are made from high quality, lead free materials and are deisgned to be used with A or B tubing (B tubing is the preferred tubing because it is more resistant to UV). The fittings can be used with hot and cold water, potable water and in sealed central heating, including heated flooring applications.