Medium Brass Tube Assortment is also known as a Hollow wire Assortment. Medium Brass Tube Assortment is a package of 5 pieces of wire with an outside diameter of 2.50 mm and a hole of aprox. 0.65 mm. All tubes or hollow wires measure approximately 3" in length. Medium Brass Tube Assortments are most commonly used for making Bushings but can be used for a variety of clock repairs.