DetailsSilicone cord is similar to Neoprene in size and shape but is a slightly softer material. Technicians looking for materials with the same properties as neoprene but with the reduced noise of a softer material should try silicone. The larger sizes of cord are used for rotor stops on brass instruments and the smaller sizes are used in woodwind repair. Use Silicone to replace corks, adjustment screws and felts on an instrument. Sold in three foot lengths.