The Connector PSLV is part of the PSLV rocket. Though it is a medium-sized connector, its very long length allows it to also function as an inter-stage fairing and will cover long payloads loaded lower in the launch vehicle.
For example, it can serve as a spacecraft extension on the Stand-Alone Laboratory which will allow other payloads (such as Crew Capsules) to be connected to it. Other connection possibilities exist.
As most with other connectors and rocket parts, it freely mates to and is interchangeable with a large variety of other non-PSLV rocket components.
PSLV, short for the Polar Satellite Launch Vehicle, was developed and operated by the Indian Space Research Organisation (ISRO). It functions primarily as a medium-lift launch vehicle, yet also serves to launch small-sized satellites into geostationary transfer orbit (GTO).