Cat fish boilies which are 24mm in size are made from liver, oils and fishmeals plus halibut pellets as well as stimulants and feed inducers. These have a massive advantage over traditional pellets. A pellet will breakdown in roughly 4 hours where as these will not be fully broken down even after 72 hours. So you can be fast asleep in your bivvy knowing that your baited zone is still a baited zone. Plus being round they are also easy to catapult to your baited zone.