This is a Gridfinity holder (2x5x6U) for a PTS200 soldering iron, with up to two extra tips (TS100/TS101) and the M2-M8 heat insert tops (One hole is slightly bigger for the M8 top).
Soldering Iron: https://www.aliexpress.com/item/1005006635552950.html
Heat Insert Tips TS100: https://www.aliexpress.com/item/1005006503495825.html