Sprue of washers to fit Lego Technic axles, intended to be used for ensuring positive location and reinforcement of removable labels. 1mm thick, the small holes are to give a better key for gluing the washer to a label.
Note that the black strong flexible material is NOT coloured all the way through and some white may be visible after separating the individual washers, I've found this can be concealed using a black marker pen.