EJ7 interlock
An EJ7 interlock was an engineering tool, made up of tritanium composites, that was used to access or close panels. With an EJ7 interlock, one could access every critical system on Deep Space 9. The tool was stored in Miles O'Brien's toolbox or in the tool locker in section five on level three.

In 2369, when Miles O'Brien was assisting Neela in repairing a system in Odo's security office, O'Brien remarked that an EJ7 interlock would be required to close the panel they were working on, due to its security seal. While looking for the interlock in his kit, he realized that it had gone missing. After a search, they found it in an access tunnel, melted into slag due to exposure to plasma. ()

O'Brien later used an EJ7 interlock to access the sealed panel containing one of the station's optronic integrators when he was working to recalibrate it under the direct of the Pah-wraith control his wife, Keiko, in 2373. ()

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Engineering tools