The introduction of nicotine salts this year has sparked the release of these ultra compact kits from all manufacturers. Most of them use disposable, refillable pods and are suitable for 50/50s e-liquids and nicotine salts. Some of them do use Sub-Ohm coils so are also suitable for High VG e-liquids. The device you choose depends on what you are looking for. It is common these are used as a stealth device to run alongside your Sub-Ohm set up, the devices are a lot less powerful hence a stronger dose of nicotine may be relevant. Nicotine salts are much smoother than traditional 50/50 e-liquids but can still pack a punch compared to your 3mg High VG vape.