These parts have become standard equipment on todays drums. They mount under the hoops and allow the drum to be completly suspended for total resonance. Each side plate has a set of universal holes that will accept ANY standard tom mount (not included - find them on our site under Tom Brackets). These are EXACTLY the same as RIMS brand iso-mounts. NOTE - This SALE model will have a slightly different mounting plate and gasket than some other models. If you need a specific match, please call us to special order for a slightly higher price.