Safety relay Harmony XPS accessories. To protect the settings on the XPSB and XPSU safety relays, the transparent front cover can be locked against opening using this tape. Each sealing tape is printed with a unique, sequential number so that the user can clearly document the setting in the delivery state. The tape is pulled tight like a cable tie and can only be released again by cutting it open. This set of 10 locking tapes serves as a replacement for the tapes included in the packaging of the XPSB/U safety relays.