The polyethylene, silicone, grease filled sleeves, are welded closed at one end, and ¾ filled with silicone grease. They are used to insulate and protect, copper conductor, twist and soldered joints. The silicone grease ensures the connection remains waterproof. Different sized sleeves, as identified by the individual colour, are used for different conductor sizes. They are supplied in packs of 10 or 25 and are mainly used for maintenance works.