Electronic safety instruments; industrial safety apparatus for the protection of workers against accidents; industrial safety apparatus for the protection of workers against injury; industrial safety instruments for the protection of workmen against accident; industrial safety instruments for the protection of workmen against injury; safety locking devices (electric); safety monitoring apparatus (electric); safety relays (electric); safety signals (audible), other than for vehicles; safety signals (luminous); safety signals in the form of flashing beacons; safety signals in the form of flashing lights