The stainless steel shackles we use on Harken® blocks are available separately. Harken forged stainless steel shackles are polished to a high luster and are stamped with the screw pin diameter. The breaking strengths shown are derived from weights supported by 80% of the length of the shackle pin, similar to the length spanned by an appropriate block's headpost.
"D" shackles are the most common type of shackle. They are best suited for aligned attachment points.
High-Resistance (HR) shackles are forged in 17-4PH stainless steel to handle high loads. They have an "HR" imprint for easy identification.