All collars come with a warning bell to help protect wildlife. The RSPB estimate that UK domestic cats are responsible for over 275 million kills each year. 55 million of these are birds! Did you realise that a cat wearing a collar with a bell will catch 41% fewer birds and 34% fewer mammals. Source: www.rspb.org.uk When fitting this collar, please ensure that you can get 2 fingers between your cat and the collar for safety and comfort. Warning - if using liquid flea treatments, please remove collar as chemical may react with material on buckle and collar.