These passing rings coordinate with the following 28mm bay window metal curtain poles: Aspect bay window curtain pole Boulevard bay window curtain pole Crescent bay window curtain pole Piazza bay window curtain pole Strada bay window curtain pole Aztec bay window curtain pole Crash bay window curtain pole Oval bay window curtain pole Torino bay window curtain pole Triangle bay window curtain pole Vienna bay window curtain pole These passing rings have a nylon insert which delivers a smooth glide action and can pass over the support and corner joints. These rings come in a pack of 8.