With a Cobra attachment to the Perlon wire or steel wire from Stas, only one condition applies: You must use the correct rail, so with the opening at the bottom. You can then simply hang the Cobra in the rail.
Because the Cobra can easily be hung on the inside of the rail, there is no obstacle to quickly remove the Cobra or to give it another place in the rail. Ideal in occasions where many changes of the hanging material take place.