50ml and 100ml short fills refer to e-liquid bottles that are partially filled with nicotine-free e-liquid and have space left for the addition of nicotine shots. These bottles are designed to comply with TPD (Tobacco Products Directive) regulations in certain regions, where the sale of nicotine-containing e-liquids in sizes larger than 10ml is restricted.

Short fills allow vapers to add nicotine to their desired strength without requiring manufacturers to sell e-liquids in smaller bottles. Here's how they work:

1. 50ml Short Fills: These bottles are typically filled with 50ml of nicotine-free e-liquid, leaving enough room to add a 10ml nicotine shot. Once the nicotine shot is added and mixed thoroughly, it brings the total e-liquid volume to 60ml, with the desired nicotine strength.

2. 100ml Short Fills: These bottles are filled with 100ml of nicotine-free e-liquid, leaving space for two 10ml nicotine shots. Adding both nicotine shots and mixing well will result in a total e-liquid volume of 120ml, with the desired nicotine strength.

The nicotine shots usually come in 10ml bottles and are available in varying nicotine concentrations, such as 18mg/ml or 20mg/ml. By adding the nicotine shots to the short fill bottle and shaking it thoroughly, you can create an e-liquid with your desired nicotine strength.

It's important to note that short fills are intended for experienced vapers who are knowledgeable about nicotine mixing and safety precautions. It's crucial to follow the instructions provided by the manufacturer and wear appropriate protective equipment, such as gloves and eye protection, during the mixing process.

Short fills offer vapers the flexibility to customize their nicotine strength while still complying with applicable regulations. However, it's essential to handle nicotine shots with care and store them safely, away from children and pets.