Which possessions are Digambara monks allowed to own?

A duster, a drinking vessel and a copy of the scriptures.

Digambara Sadhu are Jainist monks.

One of their vows is non-possession. So all they keep is a feather whisk (picchi), a water pot (kamandalu) and their scriptural treatise (sastra).

https://en.wikipedia.org/wiki/Digambara_monk

The Digambaras are strict ascetics and advocates of the unrestricted right to existence of every living being. They practise non-violence ("ahimsa") to the utmost and strive to avoid even the accidental killing or harming of other living beings, including insects. This is achieved by not moving, wearing a face mask and/or carrying whisks to sweep the ground before entering.

https://de.wikipedia.org/wiki/Digambara