Active ingredients: 4.5 Gr Imidacloprid, 2.03 Gr Flumethrin. Excipients: Titanium dioxide (E171), Black iron oxide (E172). How to apply Seresto: Take Seresto out of the wrapper inside the box and unroll the collar. Make sure you have removed any residue of the plastic connectors left inside the collar. After putting it around the dog's neck, push one end of the collar through the loop. Adjust the collar around the neck, loosely, until there are two fingers of space left. Be careful not to fasten the collar too loose: the dog could slip it off his head. Once the optimal size is reached, cut the excess portion of the collar if it exceeds 2 cm.