SCP-3660 is a black metal zipper in poor condition, similar to those found on sweaters and backpacks. SCP-3660 is non-anomalous and inert until it is pressed against the skin of a human being. In a manner not dissimilar to magnetic attraction, SCP-3660 will gravitate into the subject if held lightly against their skin. In the event of implantation, SCP-3660 will sink into the flesh until only the pull-tab is visible.