Zener diodes are usually defined as wattage required. These are a range of 1.3W voltages that will be suitable to use if you project requires any of the following pre-fixes:-
The common ones:-  BZX95, 
The not so common ones:-
All will be suitable for use with our Z1 Range. ie if your project calls for a BZX95c10v the select a 10v option from the dropdown menu as Z1+ Voltage in the case of BZX95c10v the order Z1-10v. The same analysis goes for all pre-fixes above.