the chum king is the best i caught 2 sharks using it and one insert lasted 7 hours . The insert is their formula u put in the king you dont have to freeze it or notin and if you touch it with your hand it wont smell it wont start acting like chum till it hits the water. They make many different formulas like for inn shore. You can also put live bait in their send it 30 feet down to say and tug on the rope and the king opens up letting bait out. The formulas is just like a round block i give it a 10 out of 10