It provided the ISS with one docking port for Soyuz and Progress spacecraft, and allowed egress and ingress for spacewalks by cosmonauts using Russian Orlan space suits.

The 3,580 kg (7,890 lb) Pirs Docking Compartment was attached to the nadir (bottom, Earth-facing) port of the Zvezda service module.

The Pirs module supported 52 spacewalks and served as a docking port for Russian Soyuz and Progress spacecraft ferrying crew and cargo to and from the space station.

After nearly 20 years at the International Space Station, ISS, the Pirs Docking Compartment, SO1, undocked from the nadir (Earth-facing) port of the Zvezda Service Module, SM, on 26 July 2021, at 13:55 Moscow Time (6:55 a.m. EDT) in the joint stack with the Progress MS-16 cargo ship.

Within four minutes (13:59:00 Moscow Time, according to schedule), Progress MS-16 performed a short separation burn to increase distance from the ISS.