Harken’s 5mm Stainless Steel U-Adaptor is designed to allow blocks with 10mm (3/8”) posts to be attached to swivel bases, or to other boat blocks that also have similarly sized posts.
Specifications -
Shackle pin Ø: 5mm
Weight: 13.6 g
A: 12mm
B: 11mm
Maximum working load: 567kg
Breaking load: 1134kg