Description:
Iris stop.
This is an early example marked 'Rolleiflex D.R.P.'; manufactured before 1938.
Designed to be mounted on the viewing lens to provide a check on depth of field.
This is the 6x6 version for slip-on mount lens, early Rolleiflex Old standard and New standard fitted without bayonet mount. As described in the last pictures. 
Condition:
In used condition.
Perfectly usable
As pictured
The cameras are not included in this sale!