Urgent.. Who are they? "Shadow unit" affiliated with Hamas and what is the role of its fighters?

Many in the countries of the world and the Zionist entity in occupied Palestine do not recognize the secret unit of the Palestinian resistance movement Hamas in the Gaza Strip, which is called the “shadow unit.” “Known in the Gaza Strip as the Shadow Unit.”
From its beginning until the Wall Operation in the late last century, against the Israelis in the Zionist settlements, the unit was Bassem Issa, the former commander of the Gaza City Brigade affiliated with the movement Hamas, and the brother of Marwan Issa, who was martyred in Operation Wall and was also part of a resistance cell that carried out an attack in the Zaytoun neighborhood in the northern Gaza Strip, in 1993, in which 3 were killed. Soldiers from the Israeli army, and the resistance fighters stole the weapons of the guards guarding the “Palestinian prisoners.” It was established immediately after the kidnapping of Gilad Shalit, and detained him for 4 years until the Shalit deal, then detained him for 4 more.
In 2016, Muhammad Daf announced for the first time about the unit, about a decade after its founding.
About a year after the Wall Guard operation, the spokesman for the military wing of Hamas, Abu Ubaida, revealed that during the operation one of the unit’s members was killed and 3 wounded. Others.
On December 14, 2020, during the march commemorating the 35th anniversary of the organization’s founding, which was held in Al-Katiba Square in Gaza City, two members of the unit appeared displaying a Golden Hadar weapon.
Arab sources said that most of the prisoners in the Al-Aqsa Flood operation on October 7, 2023 held by the organization are in the hands of resistance men in unity. Shadow.
During the release of prisoners in the first prisoner exchange at the end of November 23, members of the unit participated in handing over the prisoners to the Red Cross, according to Arab sources.
In the documents that appeared on the Internet after the prisoners were handed over, members of the unit were clearly visible, and at times they were emerging from their hideouts in the northern Gaza Strip, where a large-scale ground exercise ended a few days ago, “which raised many questions among the The Israelis, about how they were able to bring a large armed force that handed over the prisoners to the heart of Gaza City.