For those of you experiencing problems with the rubber nipple covers falling off (rather than those who just prefer the alternate) what is the main issue?
Is it because of the loop part being too loose and they fall off when you take the cover off the nipple, or are they falling off the nipple when in use?
It's been mentioned above about wrapping the coil of the older type rather than removing the full nipple to secure it in place. If this is done to secure the cover to stop it falling off then the rubber types could also be secured in the same manner with a zip tie, elastic band, etc
About £4 for two rubber nipple covers, about £10 and some hunting around for the metal ones.