These fit a 3" PVC pipe with no liner. YOu get all 3. If you need the center hole a different size let me know. Also I can make some for the Soapers choice silacone molds that are 2.75" Just make sure to tell me its for the smaller molds. A all thread rod will fit in the center it you do not want to use strings. You will purchase 6/32" to 1/4".