Suppose you want a 3V configuration, but not all the height of a 5/9. That's where the 3V 4/9 comes in. Using the 1" PVC, you get a dome that is made with megahubs, so it is stronger than a standard dome, and the inside height in the center is just a little less than the radius of the dome. You can use the Sonostar megahub calculator to get all the specifications. There are a lot fewer struts and hubs in a 4/9 configuration than a 5/9 configuration, too, so you could save some money. The dome starts to curve inward immediately, though, so don't be expecting to walk around on the inside edge. These are most often used as greenhouses.
If you don't see the size you are looking for click the custom kits button to submit and inquiry.
Mega Hub + Strut Kit Includes: