N-Butyric, i.e. butyric acid, is a very catchy "aroma" when it comes to summer carp and grass carp fishing
N-Butyric flavoured baits are also effective by themselves
Baits intended for method anglers contain a mixture of 9 and 11-mm
In order for the baits to be in the ideal position with the larger hooks, they have been given a high buoyancy, so they are all pop-up, i.e. floating versions