The product is specially designed for sling on various cranes. It employs die casting aluminium enclosure, which houses super bright LED cluster and the electronics, providing environmental protection, shockproof, high luminance and external long life. When triggered, it will give an alert alarm and check the oper-ation status of the sling when a problem occurs. It also can be used in electric power stations, railways and metallurgies ect. Customized colors and number of lamps can be implemented based on customer's special requirement.