This addtional piece is fastened with two M5 screws (included) to the threads in OK-VISE additional piece models. These additional pieces are available for B-, D- and F-series clamps.

Normally, additional pieces can be machined into different shapes.

In the picture additional pieces for the jaws are shown for 3 different sizes

JBA-10 ( B-series, Aluminum )
JDA-2 ( D-series, Aluminum )
JFA-18 ( F-series, Aluminum )

D-size interface (2 x M5 bolts) is used also in RMS-T type Multi-Rail RM stoppers.