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.
Stamped shackles are appropriate for low loads. For higher loads, select forged and forged high-resistance shackles instead.
Snap shackles provide one-handed operation for temporary applications that require speed and easy release. Harken® snap shackles also fit a wide variety of blocks and make them removable. Snap shackles are often used on the lower vang block so that it can be moved from the mastbase to the toerail and used as a preventer.
U-Adaptor allows blocks to be attached to swivel bases or to other blocks.