Copper end feed fittings are commonly used copper fitting, which are made from copper and require a soldered joint to connect pipes together. The pipes-to-be-joined are inserted into the fitting, which is heated. Solder fills the small gap between pipe and fitting, sealing and making a strong joint which is resistant to pulling and rotation of the pipes. This type of copper fittings wholesale requires that solder wire must be melted and fed into the joint as it is heated. Copper end feed fittings are slim and neat, inexpensive, and form a strong joint between pipes. They are probably the most reliable too for use in walls, under floors and other inaccessible locations as the joint is more secure and less likely that pipes will separate or O-rings deteriorate, resulting in leaks. However, copper pipe fittings are more difficult to use, and since the fitting must be heated using a blowtorch, there is always the danger of fire. Also, preparation of pipes and fitting is essential, and these must be cleaned with wire wool so that solder flows and coats all the surfaces being joined.