The core of a round sling can be covered by an inner signal warning sleeve. This is a red Dyneema® or orange high tenacity Polyester sleeve which serves the purpose of indicating when a sling is damaged. When the inner signal warning sleeve is visible, the jacket has been damaged already and the sling can not be used any further. This way, the core of the round sling is still usable and only the jacket needs to be repaired or replaced.