I use a lot of pellet with my boilies, I tend to buy the biggest I can get as I think you get more bang for your buck, I am using 17mm ones now, not only are they great because you can just mix them with boilies and pult the lot out together but they don't break down for 48 hours meaning if you are prebaiting with them they wont just be mush by the time they find them,and they are nuisance resistant, but if you have a ridgemonkey boilie crusher, you can also crush pellets in it making a whole variety of bits which are ideal for bags etc, they are also good for taking on liquids,