A DRAGBAR R6000 typically has 0mg/ml and 3mg/ml freebase nicotine versions with its large 18 ml e-liquid, which is also sometimes labelled as 3% nicotine.
Usually, freebase nicotine is a little slowly absorbed but stays in your system a bit longer, which offers a high strength and a strong throat hit, while nicotine salts are milder for beginners.