The rubber comes with the holes pre-punched. I believe it is also good to buy a matched pair so everything is balanced nice. There are two different ply thicknesses available and are available from Shavers in Stonewall,Mb. If you give him a call, he will fax you an up-to date price list. I asked him why he doesn't post his parts list on this site, and he said he always wanted to but he always intended to make it look like a more tidy catalogue before he did. I told him that I thought everyone on this site was just an average joe and wouldn't mind.