The descriptions of these electric inserts indicate that they are available in 120v and 240v. However, I don't see the option to order the 240v version. Please advise how to do so?

The voltage for the unit can be 120v, 208v and 240v. On the unit is a voltage selector switch that will allow the user to change the voltage. If you have any further questions we recommend that you give us a call. Thanks.