Range Ring Threshold

The "Range Rings" option under "Custom Feeds" in Gibson Ridge need to have a user configurable Threshold option.  This allows the user to determine at what zoom level the rings appear.  That way when the user zooms out the rings disappear, but when the user zooms in on particular point the range rings appear again.  Right now I use some third party rings configured in a text file and I have my threshold set at 50.  But I like to manage as many as my parameters in one place if possible.  I'd prefer to use your range rings, but I need the threshold option.  Thanks