The Mazzella EN4 nylon endless web sling has heavy-duty four-ply webbing for lifting fragile or irregularly shaped loads with vertical, choker, or basket configurations in construction, general industry, and other low-heat applications. The nylon webbing is soft to avoid scratching fragile or delicate loads. This web sling is flexible, conforms to irregularly shaped loads, and has a better strength-to-weight ratio than a wire rope or chain sling. This nylon web sling resists several chemicals, including alcohols, aldehydes, strong alkalis, ethers, hydrocarbons, ketones, oils, detergents, and sea water. However, it does not resist acids or bleach agents. The stretch of a nylon sling at its maximum load capacity is approximately 8-10%.

This endless (also called type 5 or grommet) sling is made of a continuous loop of webbing formed by joining the ends of the webbing with a load-bearing splice, and can be used in vertical, choker, and basket lifting configurations. The load-bearing or wear points of an endless sling can be rotated each time it is used, which can help increase its life when compared to an eye-and-eye web sling. The four-ply construction is stronger than a one- or two-ply web sling, and the sling's heavy-duty webbing is denser than light-duty four-ply webbing. When the sling's red warning yarn becomes visible, this indicates the sling is no longer fit for use. This sling meets American Society of Mechanical Engineers (ASME) specification B30.9 and Occupational Safety and Health Administration (OSHA) specification 1910.184.

Slings are used to lift heavy objects for industrial applications. Types of slings include web slings, wire rope slings, chain slings, and mesh slings. The appropriate type of sling for an application depends on the strength-to-weight ratio, flexibility and resistance to bending, resistance to abrasion and cutting, resistance to crushing, resistance to stretching, and resistance to high temperatures and other environmental stressors. Slings have one, two, three, or four legs; or a continuous loop of webbing. Legs are support branches that extend from a single point at the top of the sling to the item being lifted so the weight of the load is distributed evenly among the branches. Slings have eyes (loops) or alloy steel fittings on the ends.

A vertical lifting configuration connects a crane hook directly to a load with a single, vertical sling, usually by means of a hook. In a choker configuration, the sling wraps entirely around the load, and one loop passes through the other to form a slip noose, or choker. In a basket configuration, the sling passes under the load and both ends of the sling connect to the crane hook. Load capacity is the maximum weight to be lifted in a vertical configuration. The capacity in a choker configuration is approximately equal to the vertical capacity times 0.8. The capacity in a basket configuration, with sling ends at a 90-degree angle, is approximately equal to twice the vertical capacity. Load capacity in a basket configuration decreases if the angle of the sling is less than 90 degrees. For example, a sling with a capacity of 2,000 lb. in a vertical configuration will have an approximate capacity of (2,000)(0.8)=1,600 lb. in a choker configuration and an approximate capacity of (2,000)(2)=4,000 lb. in a basket configuration, if the sling ends are at a 90-degree angle to the load.

Mazzella Lifting Technologies manufactures lifting solutions including slings, cranes, and hoists. Founded in 1954, the company is headquartered in Cleveland, OH.