This sample pack consists of one each of Sonostar's custom-designed megahub dome connectors. They are designed to fit either 1" or 1 1/2" Schedule 40 PVC pipe. If you're thinking of building a megadome, and you want to evaluate the specifications, this is a good way to start. The pack includes one each of the 4-star, 5-star, and 6-star megahubs.