Eye & Eye vs. Endless Flat Slings: Which Configuration Suits Your Application?

A rigging supervisor faces a common decision: the job calls for a flat sling, but there are two configurations on the shelf. One has sewn eyes at both ends. The other is a continuous loop with no eyes at all. Both are rated for the same capacity. Which one should be used?

This scenario plays out daily in workshops and construction sites. The choice between an eye & eye flat sling and an endless flat sling can affect rigging speed, sling longevity, and even safety outcomes.

Lishenflex has been manufacturing synthetic flat slings for decades, and our experience shows that understanding the operational differences between these two configurations is essential for selecting the right tool for the job. While both share the same high-tenacity polyester construction and 7:1 safety factor, their distinct designs suit different lifting scenarios.

1. Core Design Differences

The fundamental distinction between eye & eye and endless flat slings lies in their construction and attachment method.

1.1 Eye & Eye Flat Slings (Type 3 and Type 4)

An eye & eye flat sling features a sewn loop, or "eye," at each end of the webbing strap. Under ASME B30.9, there are two subtypes:

• Type 3 (Flat Eye): Both eyes lie in the same plane as the sling body. This is the most common configuration for general-purpose lifting.

• Type 4 (Twisted Eye): The eyes are turned 90 degrees to the sling body. This design provides a better fit on crane hooks and forms a superior choker hitch.

The sewn eyes provide dedicated attachment points that connect directly to hooks, shackles, or other rigging hardware without additional connectors.

1.2 Endless Flat Slings (Type 5)

An endless flat sling—designated Type 5 under ASME B30.9—is a continuous loop of webbing joined by a load-bearing splice, with no fixed eyes or terminals. The entire loop is a potential attachment point. Because there are no predetermined eyes, the rigger can rotate the sling to change the load-bearing point, distributing wear across the entire webbing.

2. Performance Comparison

2.1 Strength and Capacity

For identical dimensions—same width, same ply count, same length—both configurations offer identical rated capacities. According to Certified Slings & Supply load limit data, a 2-inch, single-ply eye & eye sling and an endless sling of the same width share the same vertical, choker, and basket ratings.

The ply count (number of webbing layers) determines capacity, not the configuration. A 2-ply endless sling has the same strength as a 2-ply eye & eye sling.

2.2 Wear Patterns and Service Life

This is where the two configurations diverge significantly.

Eye & eye slings concentrate wear at the sewn eyes and the splice areas. Over repeated use in the same hitch configuration, these fixed points experience accelerated abrasion.

Endless slings can be rotated with each use, moving the load-bearing point around the loop. This distributes wear evenly, typically resulting in a longer service life compared to eye & eye slings used in the same application.

Jergens product literature confirms this: "The endless configuration offers versatility, providing multiple wear points for more even wear across the sling, increasing the lifespan of the sling."

2.3 Attachment Convenience

Eye & eye slings offer faster attachment in standardized lifting tasks. The pre-formed eyes connect directly to hooks or shackles, eliminating the need for threading or extra connectors. This speeds up repetitive lifts.

Endless slings require a tertiary means of attachment—a hook, shackle, or other fitting—since there are no built-in eyes. This can add rigging time in some applications, though the flexibility of the loop compensates in irregular lifting scenarios.

3. Hitch Configuration Compatibility

Both configurations can be used in all three primary hitch types—vertical, choker, and basket.

3.1 Vertical Hitch

Both work equally well. The eye & eye sling attaches directly to the hook via its eyes. The endless sling loops over the hook or through a shackle.

3.2 Choker Hitch

Eye & eye slings—particularly Type 4 with twisted eyes—form a superior choker hitch. The twisted eye orientation allows the eye to sit properly on the hook without excessive twisting of the sling body.

Endless slings can be used in a choker configuration by passing one end of the loop through the other, but the absence of a fixed eye makes the setup less standardized.

3.3 Basket Hitch

Both work well. The endless sling offers an advantage in basket hitches over irregular loads, as the continuous loop can be adjusted to find the optimal balance point.

4. Selection Guidance

Mazzella Companies offers this practical guidance: "Typically, it comes down to personal preference. You can do every type of hitch with an endless sling that you can do with an eye & eye sling." The choice is less about capability and more about operational priorities.

Lishenflex's field data confirm that endless slings typically outlast eye & eye slings in high-frequency applications due to their ability to distribute wear, while eye & eye slings remain the preferred choice for operations where fast, standardized attachment is the priority.

5. Summary and Practical Recommendations

Choosing between an eye & eye flat sling and an endless flat sling is not about strength—both are equally strong. It is about matching the configuration to your operational workflow and maintenance philosophy.

Key takeaways:

1. Identical capacity—same width, same ply, same WLL

2. Eye & eye excels at fast attachment—ideal for repetitive, standardized lifts

3. Endless excels at longevity—rotatable wear points extend service life

4. Both work in all hitches—vertical, choker, and basket

5. Type 4 twisted eye is best for choker hitches—provides superior hook fit

6. Endless is preferred for irregular loads—continuous loop conforms better

Lishenflex manufactures both eye & eye and endless flat slings to EN 1492-1 and ASME B30.9 standards, using high-tenacity polyester webbing with clear color-coded capacity markings. Our products are available in single-ply, double-ply, and multi-ply configurations, with widths from 25 mm to 300 mm.

If you need assistance determining which flat sling configuration is right for your specific lifting operations—or need help establishing an inspection schedule for your sling inventory—please send an email to sales@lishenflex.com, and our technical team will provide one-on-one support.