Appear to do the job, even to a sceptic
Being sceptical of this type of product our vet gave a small sample pack to try. Cats enjoyed them and could see that they were actually crunching up the biscuits as designed and not just eating whole . Follow-up dental checks seem to show these are having a positive effect. Expensive and the cats do seem to go off them when the pack has been open and used for a while, so best when fresh and kept air-tight. For best effect serve these separately AFTER the cats have eaten their main meal.