What kind of keys did Qaroon have?

In the following verse we read about Qaroon’s keys.

28:76 Qãroon (the slave driver) was one of Moses’ people who betrayed them and oppressed them. We gave him so many treasures that the keys thereof were almost too heavy for the strongest band. His people said to him, “Do not be so arrogant; GOD does not love those who are arrogant.

إِنَّ قَارُونَ كَانَ مِنْ قَوْمِ مُوسَىٰ فَبَغَىٰ عَلَيْهِمْ وَآتَيْنَاهُ مِنَ الْكُنُوزِ مَا إِنَّ مَفَاتِحَهُ لَتَنُوءُ بِالْعُصْبَةِ أُولِي الْقُوَّةِ إِذْ قَالَ لَهُ قَوْمُهُ لَا تَفْرَحْ إِنَّ اللَّهَ لَا يُحِبُّ الْفَرِحِينَ

The verse informs us that the keys were so heavy that it was almost too heavy for even the strongest band. But is this a band of men or a physical band? Let’s take a look at the Arabic to figure it out:

From the Arabic we see that the word for “band” is “بِالْعُصْبَةِ” which comes from the word “عُصْبَةِ” which means: a band; troop; gang; party; group. We see the same word used in the following verses: 12:8, , and .