Holds a solution of water, sugar and boric acid. Designed to sit up against a baseboard so it will be out of the way. Sloped sides encourage ants to climb up to the reservoir. When printed at 100%, it is fairly small (approx. 2" long), so it may need to be refilled with solution daily. The standard formula is 1 cup water + 8 teaspoons sugar + 1 tsp boric acid. This mixture has worked well for us. The ants go back and poison their colony after consuming it.