It is designed according to the standards of EN71 Figure 18. It is design according to the EN71 Figure 18.A rectangular opening measuring (1,02 ± 0,02) mm by (1,15 ± 0,02) mm in the end of the slotted cap establishes two reference dimensions. The sensing head is recessed (0,38 ± 0,02) mm below the end cap.There is a distance of (0,12 ± 0,02) mm between it and a return spring.