An UPSI trolleybus assembly is used to hang the contact wire to the messenger wire. UPSI in Russian stands for Unified Insulated Sliding Hanger. It consists of a clevis which hangs on the messenger, the IPK composite insulator and a ZPV-2 contact wire clamp with threaded-in clevis.

UPSI hanger can have any other insulator of the "short"-type. But this exact complectation is the most common (exept for Moscow where only foberglass insulators are used)

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