Description: Stainless Steel 304 D Shackle, also known as chain shackles, d shackles, or shackles, both referring to the "D" shape design Marine-grade corrosion resistant, strong, sturdy, and very duarable even in the grimy, wet conditions found during off-roading Narrower than a bow or anchor shackle and generally have a threaded pin or pin close Smaller loop, designed to take high loads primarily straight in line -- Do not use it for side or racking loads Well suited for attaching ropes, cables, straps, chains and other fastenings for sailing, rigging, lifting and other different situations on the adventurous trail Specification: The length "4mm" is referring to the thread diameter like M4, which also presents the shackle strength. For details such as breakload and overall size, you can check in the chart. M4 Thread diameter: 4mm; Breakload of M4 shackle: 500 kg/ 0.5 t/ 1100 lbs M5 Thread diameter: 5mm; Breakload of M5 shackle: 800 kg/ 0.8 t/ 1763 lbs M6 Thread diameter: 6mm; Breakload of M6 shackle: 1100 kg/ 1.1 t/ 2425 lbs M8 Thread diameter: 8mm; Breakload of M8 shackle: 2000 kg/ 2 t/ 4410 lbs Package Includes: 1 piece shackle Note: 10mm-14mm diameter of 304 stainless steel shackle is also available in our shop, please check on it.