I have the CL domes they were hard at first then I got use to them. They stay on now with no struggle except when I try to do chores around the house they would fart and deflate. So I try find time to stay still and lean back a little so the suction would stay.
Also, lucky you I just found something on ebay related to the foam rings but are made of silicone. I do not sell these nor need them. Click the link below:
http://www.ebay.com/itm/130712586138?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
The last time I saw it bidding on was .99 cents and almost $2 for delivery. Way much cheaper than the nb rings. I ask for measurements its 6 in from top to bottom and 5.5 in left to right. Just about fit the CL domes.
Also, lucky you I just found something on ebay related to the foam rings but are made of silicone. I do not sell these nor need them. Click the link below:
http://www.ebay.com/itm/130712586138?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
The last time I saw it bidding on was .99 cents and almost $2 for delivery. Way much cheaper than the nb rings. I ask for measurements its 6 in from top to bottom and 5.5 in left to right. Just about fit the CL domes.