These aluminum hourglass sleeves are crimped to join two cables. For construction of oil containment boom and silt curtains, these sleeves are used in pairs to form end connector loops on cables. The cable is fed through the two open channels in the sleeve, and a crimping tool is used to sqeeze the sleeve tightly around the cable, fastening the two cables together.
1.25 in x 1.06 in x .69 in with .36 in inner diameter channels -- suitable for 5/16 in cable
These hourglass sleeves are sometimes referred to as farrules.