An issaron is a Biblical unit of measurement roughly equal to 2 quarts or 2 liters.

The issaron represents one day's ration and is identified as one 1/10 ephah.

The issaron is equated with the omer which is the amount of manna that the Israelites collected in one day.  Issaron refers to measures of fine flour.

Issaron is not so much a measurement as it simply means 1/10.  Because it is 1/10 ephah it was used in reference to this amount simply through the abbreviation issaron.