What Is the Difference Between Eye & Eye and Endless Flat Slings?

A rigging crew is preparing to lift a load. The flat sling they pull from the rack looks right for the job—but there are two very different configurations on the shelf. One has eyes at both ends. The other is a continuous loop. Which one should they use?

This scenario plays out in workshops and construction sites every day. And the wrong choice can mean unnecessary wear, slower rigging times, or even a compromised lift.

Lishenflex has been manufacturing synthetic flat slings for over two decades, and our experience shows that understanding the difference between eye & eye and endless configurations is one of the most fundamental—and most overlooked—aspects of sling selection. Each design has distinct advantages, and the right choice depends on the specific lift geometry, load characteristics, and operational priorities. As noted in Holloway Houston's web sling guide, selecting the correct configuration is the first step in choosing the right equipment for your lift.

Eye & Eye Flat Slings—The Versatile Workhorse

An eye & eye flat sling—also referred to as a double-eye sling—features a sewn loop, or "eye," at each end of the webbing strap . These eyes provide built-in attachment points that can be connected directly to a crane hook, shackle, or other rigging hardware.

Holloway Houston categorizes eye & eye slings into two subtypes under ASME B30.9 :

The twisted eye design is particularly valuable in choker applications, as the orientation allows the eyes to sit properly on the hook without excessive twisting of the sling body . This reduces stress on the webbing and extends service life. As Lift Solutions Holdings notes, eye & eye slings can be used in all three hitch configurations—vertical, basket, and choker—making them one of the most flexible options in a rigging inventory.

Key advantages of eye & eye flat slings:

Quick attachment—built-in eyes eliminate the need for separate connectors in many applications

Length adjustability—as one industry overview notes, eye & eye slings offer the advantage of length adjustability for different lift geometries

Versatility—suitable for vertical, basket, and choker hitches

Endless Flat Slings—The Continuous Loop Solution

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

Holloway Houston emphasizes that this rotation capability significantly extends the life of endless slings compared to eye & eye configurations . McMaster-Carr's product guide similarly notes that endless slings last longer than slings with eyes because they can be rotated to change the load-bearing point.

Key advantages of endless flat slings:

Extended service life—wear points can be rotated, avoiding concentrated degradation

Economical—often lower cost than eye & eye slings for comparable capacity

Versatile attachment—can be used with hooks, shackles, or other fittings as the application requires

Suitable for all hitch types—vertical, choker, and basket configurations

Endless slings are particularly well-suited for applications requiring a wide grip on large equipment, such as lifting pipes, or where the lifting points are not precisely defined . However, as noted by Zoho Hoisting, they do require a tertiary means of attachment like hooks or shackles, since there are no built-in eyes.

Head-to-Head Comparison

The choice between the two configurations ultimately comes down to the specific lift requirements. If your operation involves frequent changes in lift geometry and quick attachment is a priority, eye & eye slings offer clear advantages. If you are lifting irregular loads where the bearing point shifts, or if you want to maximize service life in a high-frequency application, endless slings are the superior choice.

Standards Compliance and Inspection Considerations

Both eye & eye and endless flat slings are covered under EN 1492-1:2000+A1:2008 , the European standard for flat woven webbing slings made of man-made fibres for general purpose use. This standard specifies safety requirements, methods of rating and testing, and marking requirements for flat woven webbing slings in the width range of 25 mm to 450 mm inclusive. It also confirms that flat woven webbing slings conforming to this standard are suitable for use and storage in the following temperature ranges: polyester and polyamide -40°C to 100°C, and polypropylene -40°C to 80°C.

Under ASME B30.9, all synthetic slings—both eye & eye and endless—must undergo regular inspections. As Mazzella Companies outlines, three levels of inspection are required:

Key removal criteria per ASME B30.9 for flat webbing slings include missing or illegible identification, acid or caustic burns, evidence of heat damage, holes or tears that expose core yarns, broken or worn stitching in load-bearing splices, excessive abrasive wear, knots, discoloration or brittle areas indicating chemical or UV damage, and damaged fittings.

ASME B30.9-5.9.5 specifies the frequent inspection requirements for web slings, which include checks for broken or worn stitching in load-bearing splices—a critical point for eye & eye slings where the eye splice bears the full load. Endless slings, by contrast, require particular attention to the load-bearing splice where the webbing ends are joined. Both configurations require immediate removal from service if any of these conditions are detected.

The British Standards Institution (BSI) , as the publisher of BS EN 1492-1, provides the authoritative framework for flat webbing sling compliance in the UK and European markets, while ASME B30.9 serves as the primary standard in North America. Per ASME B30.9, employers are required to maintain records of the most recent thorough periodic inspection, and failure to maintain inspection records is one of the most common issues that can prevent a company from reaching full compliance with workplace safety regulations.

Summary and Practical Recommendations

Choosing between an eye & eye and an endless flat sling is not a matter of one being "better" than the other—it is about selecting the right tool for the job.

Three recommendations to implement:

Audit your inventory—determine which configuration is most frequently used and identify gaps

Train your team—ensure riggers understand the difference and can select the right type for each lift

Inspect both configurations regularly—pay particular attention to splices on endless slings and eye stitching on eye & eye slings, as these are the highest-stress points

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 a range of widths from 25 mm to 450 mm and rated capacities from 1 ton to 10 tons, with reinforced eye options for demanding applications.

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.